What a really nice game with a lot of potential. I may have a few suggestions of how to improve it.
Add the ability to equip and create equipment. What those things do is up to you.
Add mora as third resource needed for the equipement creation and upgrade. Mora can be obtained from raids or by killing (not capturing).
Add ability to build outposts. You should be able to add different things to the outpost to change its behaviour.
Add ability to build brothels on the map. This will be the main source of mora income later in the game. You should unlock this by capturing receptionis from Mondstad or Liune.
You should be able to build brothel in the outpost and send heroine there. There will be a chance that an enemy will try to recapture the heroine so there is need for guards.
The receptionist will manage all brothels.
The saying goes if there is a will there is a way. Rich perverts are keen to throw mora just to have sex with someone famous as heroines.
The amount of mora earned is dependent on the sex abilities of the heroine, the amount of elemental energy, the level of obedience, the requested service and the mental state of the heroine. Not everyone wants to have a sucubus. Some want to have obedient bitch that hates what she is forced to do.
You should be able to request multiple services at once but it will cost more than single service. A wealthy guest once a week is a good compromise.
You have already predicted the childbirth of a human as you added a placeholder so I will leave the rest of it to you.
Change how the obedience works. How I see this is that every heroine has their achievemnets. For example amount of births or children produced. The info about killed enemies on the heroine just begs to add achievement for it like "eye for an eye" when the two amounts equal. The rest I will leave it to your imagination. Obedience should not be correlated with elemental energy. The elemental energy system on itself is good but right now it restricts what is possible. What I suggest is to add a willingness or will of a heroine. The stronger the will the stronger elemental energy.
This comes in combination with brothel as to what heroine can do and what services to perform. The more achievements the heroine has the more obedient she is as this marks her milestones of acceptance.
My personal kink is to add the ability to milk and have bigger breasts. The milk will drain elemental energy of the heroine. You can obtain more milk by enchanting the heroine breasts to be bigger but the elemental drain per session will remain the same. You can do it similar to the game where you need specific items and mora to level it up.
Milk can be sold for mora or nurse the young. Lactation should be able to start due to childbirth and then diminish after some time or induced by some drugs.
Also you could add the ability for hilicurls to be in an infant stage. Depending of the quality of the milk consumed (elemental energy) the young could become stronger. It should consume 1 liter of milk per week after which the hilicurl will become an adult. The heroine will start lactating one week before birth so it can be collected.
Maybe there is a model for interpolation of frames between two key frames. This way you can add smooth animation.
I know this is a lot but hey, it is your game and you can do whatever you want. The amount of images variation will be huge but this is why you use AI for it.
Thank you for the suggestions.
Actually I have considered mora and you can find them in "golden house", a hidden place. And in my plan, mora was related to a brothel, which will be built after you beat the ship outside Liyue Harbor. There are several reasons why this system has not been implemented. First, I don't know how to spend mora. If it is to exchange ore and food it looks redundant. Second, just as Pauloco mentioned a brothel seems weird in this game. This also ruled out the idea of hiring human units like kaigari. Third, I haven't found a way to create genshin-style human male CG. They look too modern to me and I think that's weird.
As for outpost, I will allow constructing defensive buildings once I finish the code for battle terrain.
Cooking will be added in the future and maybe lactation.
Blacksmith will also be added in the future. This may allow you to craft weapons or just upgrade all hilichurls' skills. I haven't decide it yet because the choosing weapons would make the UI even more incomprehensible...
Diversifying the way of obedience is a good idea but this will need lots of in-game text work so it is not considerable now. Or you need to guess the requirement of each girl, which would be a disaster.
I don't want each hilichurl to have it's own attack and defence value, because a lot of code needs to be changed if so. And this will also make the team formation UI more incomprehensible.
I tried several AI interpolation models but somehow none of them worked for pony model.