Your comments

Already on the todo list.
As usual, no promise on the delivery date though. ;)
Sorry for getting back so late. Unfortunately I still haven't a clue of what might be going on. :(
Do you have the 1 second delay on font stored locally or on front downloaded from an external server (e.g. Google fonts) ?

As for the error in the console: from what I understand of Cross-Origin Resource Sharing, the HTTP header allowing the access has to come from the server hosting the font, not from Ubooquity server. So there is nothing I can do here. Let me know if I missed something.
Good point, I'll have the "-headless" parameter to automatically set the "java.awt.headless" flag so that you don't need to add it manually.
I tried to reproduce the problem o nmy Raspberry Pi (under Raspbian), but to no avail.

And since the "Set password" button just takes you to the "/admin" page (it doesn't do anything complex), I still haven't a clue as to why you have this problem.

Could you describe the setup in which you reproduced it ? (browser, operating system, device...)