Hi Babynus!
I understand that a major overhaul of the GUI is out of scope (at least) at the moment.
One thing I've seen, and appreciate, in new webapps is an "in-context tour popups signs" system (don't know any less-complex name to name it

)
As an example I attach a few print screens from google maps, showing the "Tour" thing.
If such thing is possible with not-so-big-an-effort, it could be a nice-to-have. Mainly when dealing with clients, or occasional contractors, which are going to use "our" Projeqtor only eventually, anf therefore need to get started quite fast (it's hard to convince them to spend many hours/days learning the system if they're just going to use it every once in a while).
It could be implemented gradually: perhaps explaining menu, sidebar, status bar and console, for example. And then extend it to specific screens: what can you do in "Tickets" screen, "Work allocation" screen, "Documents" screen, and so on...