There's a few things, but probably the one thing that I would consider a 'hold up' for what I was working on at the time is Priscilla Rich/Cheetah (#2)
https://f95zone.to/threads/renpy-su...unity-development-thread.144779/post-11218158
I have a small handful of sprites for her, but not what I'd consider a fully usable set. And my art skills aren't that good... I can photoshop to a point, but that only gets me so far.
This dovetails into a larger problem, a lack of an art director for this project. What I mean by this is someone that is willing to take the time to 'curate' the various contributions in the SU Sprite Re-Mix/Fanart thread, and pick out 'usable art' from a day to day storytelling perspective, that will blend well with existing artwork.
For newly added characters, this SEEMS like it'd be easier, but there are a number of 'routine' poses/expressions that would be needed, and then if there are multiple costume variations, well you need the same poses/expressions for each costume for things to work well. This gets more complicated with sex scenes...
Which is why I keep thinking that going the 3d rendered route using Daz Studio might be a LOT easier and faster in the long run. But of course a lot of people like the 'hand drawn' style sooo...
The AI generated route seems like it has potential, but the 'consistency' thing and finding someone that will crank out a bunch of stuff back to back day after day and take the time to generate usable sets of artwork in game terms, yeah...
Setting up layeredimage also takes a bit of time, and is a bit of a skill unto itself, but this is more 'tedious work' than anything. Once you understand how Ren'Py handles this, it's not that hard. But that's a bit more of a coding thing than an art director thing, although the art director needs to understand what's needed.
In short, we need more dedicated people to help with this project.