Hey, Katarsys, maker of Kplug for Koikatsu, is working on an Ai Shoujo equivalent, which typically means custom positions as it did in Kplug, so I wouldn't count anything out just yet. We'll just have to wait and see what the modding community comes up with before they move on to whatever Illusion has in store next.
Not sure what you mean by Kplug, the Koikatsu game failed to engage me long-term.
Editing animations is possible now with Enamoroah's SB3UGs which he updated to support AI-Shoujo (I wrote a tutorial on the Modding thread here). The problem isn't inaccessibility. The problem is the annoying format.
Instead of the loops being setup like they were in say Honey Select, PPD, or SBPR -- where you have a pre-engaged animation, a roughly 5-8 second loop animation, with 2-3 variable animations (usually different head positions for the female), then an alternate more aggressive version with 2-3 variable animations, a pre-climax loop, then a climax loop, followed by a post-climax idle... For a total of 10 to 12 animations per position...
In AI you have a pre-engaged loop, but then you have a gambit of random 1-3 second loops for the initial insertion/thrust position, then the main loop will have about 12-20 smaller animations that aren't exactly in the same spot in the .unity3D assets files, same goes for the pre-climax loop, then the climax loop typically has 2-3 variations and the post-climax idle. Yet this time around, this is only one model at a time, and the models are headless, all face/head animations are totally separate, as well as the hair bone physics.
That means you are editing at least 28-30 tiny animations, per body (56-60), and if you don't want the generic facial expressions included with the animation, then another (56-60 face animations) and if you change the head positions, then you have to change the hair bones as well. The process is inundating without being able to just throw the models into a 3D software like Blender then import them into the Unity Anims plug they used to export in this format. There is no shortcut without source code presently. The way it stands now, you need to edit these animations 1-3 seconds at time and in multiple parts. Someone was trying to describe a method to me using "anchor points" and loading all models (male, female, male head, female head, male hair bone, female hair bone, male phallus) into an animation in Blender and positioning them in the editor then locking certain vertices to coordinates so the anchor points didn't move in relation to the meshes in the environment. Then you can create a full 60 second animation or whatever in the dopesheet, then export the individual model's animations into their own FBX to recompile into the .unity3D file format then update through SB3UGs...
I understand what they meant, but I found no way to do it, and they weren't the best teacher, nor very patient with others. I also noticed they do custom animations and stuff on Patreon and DeviantArt for fees... So... I guess sharing their knowledge is not exactly profitable in their life.
I started a "hardcore" mod by request, where I was just updating 4 positions to be more rough and invasive in appearance, but I haven't got a working fluid animation yet. When/if I complete this, I also promised to help another person with a "futanari" mod, but I feel this may never happen presently.
Another hurdle without source code is editing in extra animation slots without overwriting current anims (which presently is the only way to incorporate them). These are hardmod only options right now.
So again, remaining optimistic, but we'll see. It seems most of these things only appear long after the game has fallen out of the scene. This title is slowing down already it would seem and it's only what 4 months old? Now if we do see a Steam release, then we'll see a more active community and scene. All that is up to Illusion and Fakku.