There are a lot of things I’d certainly like to see from Paper2d: I’ve monitored the 4.10 build on the github and there is activity in the paper2d plugin stuff. Hopefully there can be more but I think the best way we can get paper2d a full dev support is by making more paper2d games and showing that we’re trying to make something more than just a small simple game.
I’m currently preparing a WIP thread for the game I’m working on which is a huge paper2d based game and hopefully that’ll garner more attention for it.
Show Epic that we want these changes because we’re making something Unreal, right? 
If a dev does look in here: Animation Notifies would be great. Grouped Sprites improvement for procedural content (collision improvement, better access to the instances created for more than just transforms, removal of instances to work more robustly). Allow us to set Z-render layering (for transparencies) on render shapes inside the render geometry in the sprite editor (so we don’t have to make two of the same art assets with different Z layers and different render geometries and group them). Collision check improvements. Fix a weird bug that happens that if you collide with someone, collision works properly on both ends, but if a collision object collides with you, if you’re not inputting anything, all logic for collision is ignored. (seems to only happen with paper 2d stuff.) and that would be about it for my improvements list. I’m sure there’s more but for right now those are the things that force a really convoluted work around that should def be easier for implementation.