You should be able to make it work ;) 

Backup your orginal ubooquity apache configuration file somewhere (or remove the symbolic link with a2dissite if you setup it with a2ensite).

Create a new one "ubooquity.conf" in /etc/apache2/sites-enabled and copy paste this configuration below (I replace my settings by yours) :

ProxyRequests Off                                                                                                                                                          
                                                                                                                                                                           
<Location "/newsstand">                                                                                                                                                   
ProxyPass http://localhost:2202/newsstand
ProxyPassReverse http://localhost:2202/newsstand
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                   
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/newsstand/admin">                                                                                                                                              
ProxyPass http://localhost:2203/newsstand/admin                                                                                                                           
ProxyPassReverse http://localhost:2203/newsstand/admin                                                                                                                
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                 
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/newsstand/admin-res">                                                                                                                                          
ProxyPass http://localhost:2203/newsstand/admin-res                                                                                                                        
ProxyPassReverse http://localhost:2203/newsstand/admin-res                                                                                                                 
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                                
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/newsstand/admin-api">                                                                                                                                          
ProxyPass http://localhost:2203/newsstand/admin-api                                                                                                                        
ProxyPassReverse http://localhost:2203/newsstand/admin-api                                                                                                                 
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                        
</Location>     

Don't forget to restart apache with : 

sudo service apache2 restart

Go to the ubooquity URL and refresh (clear the cache if no data appears).

If this does not work, delete the file created above and reactive your old configuration file. 

PS : we may use Apache mod_rewrite to simplify but i'm not an Apache expert :/

It seems to work for me now with this configuration file (ubooquity.conf in /etc/apache2/sites-enabled/ ) :

ProxyRequests Off                                                                                                                                                          
                                                                                                                                                                           
<Location "/ubooquity">                                                                                                                                                   
ProxyPass http://localhost:2202/ubooquity                                                                                                                                
ProxyPassReverse http://localhost:2202/ubooquity                                                                                                                         
AuthType Digest                                                                                                                                                            
AuthName "you shall not pass"                                                                                                                                                       
AuthUserFile '/etc/htpasswd'                                                                                                                                               
Require user gandalf                                                                                                                                                     
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/ubooquity/admin">                                                                                                                                              
ProxyPass http://localhost:2203/ubooquity/admin                                                                                                                           
ProxyPassReverse http://localhost:2203/ubooquity/admin                                                                                                                
AuthType Digest                                                                                                                                                            
AuthName "you shall not pass"                                                                                                                                                 
AuthUserFile '/etc/htpasswd'                                                                                                                                               
Require user gandalf                                                                                                                                                    
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/ubooquity/admin-res">                                                                                                                                          
ProxyPass http://localhost:2203/ubooquity/admin-res                                                                                                                        
ProxyPassReverse http://localhost:2203/ubooquity/admin-res                                                                                                                 
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                                
</Location>                                                                                                                                                                
                                                                                                                                                                           
<Location "/ubooquity/admin-api">                                                                                                                                          
ProxyPass http://localhost:2203/ubooquity/admin-api                                                                                                                        
ProxyPassReverse http://localhost:2203/ubooquity/admin-api                                                                                                                 
Allow From All                                                                                                                                                             
Satisfy Any                                                                                                                                                                
</Location>     

Hope that helps !