The big picture feedback is that often there is an alignment between “I have a lot of ideas for unique UX I want to implement” and “I want to wake up this morning and work on this all day.” IMO just copy AE’s UX affordances first if your goal is to make something you want other people to use. Blender spent a decade in the doldrums until it found an audience the moment they relented and copied Maya and Unity’s superior, conventional controls.
@clementpiki I second this advice and strongly suggest to document it as a guideline for your project as soon as possible. Surf on the shoulders of AE's UI giants!
Otherwise a small but vocal number of devs users who implicitly love FOSS software will end up rationalizing all the little UI quirks as features. Worse, their lack of expertise in UI design will be proportional to their level of energy and post length on all your communication channels. It's the epitome of bike-shedding. But if you just standardize on "whatever AE does" nobody will spend a moment advocating for putting quirks into the UI. (Plus they'll be very forgiving about quirks since it's obvious that getting the UI to work exactly like a proprietary piece of software is a very difficult problem.)
It's like walking into a car dealership and they tell you their car is free, and you ask where the seats are, and they say "why, on the ceiling, of course. We didn't want to copy all those other car companies."
You pop open the hood and there's no engine. "Where is the engine?" "On the roof!"
"Where is the gas tank?" "It's that plastic bag you keep on your lap."
The visual look can be protected, some novel or distinctive features can be patented or trademarked (like Amazon patented one click purchases??), but the core functionality is up for grabs
The big Oracle / Google lawsuit a few years back is a good example. Google rebuilt the Java compiler to avoid paying licencing fees (?), and argued that because they did it from the API specs, without referring to the existing code, it was aboveboard. The functionality is not copyrightable, just the specific implementation.
If you can't duplicate it, I can send you a short screen recording (I would just upload, but where do you upload <1MB binary files nowadays that isn't an ad-filled mess?)
it has a web player built in as well.