If there's a potential a potential new game with an anal-only path in development, then I will always be invested.
At some point you should consider making a Discord server or something for Patrons to provide feedback or something. Until then I'll keep most of my feedback here, since it's better than Patreon's comment section.
That's amazing to hear. Thanks to Anal-Lover and Arabesque for the extra nudge 

. So with that I have a few others suggestions:
1) I hope the 
missionary sex scene that gives strength will also eventually receive an anal version.
2) You have previously said "ALL main LI are virgins, until they engage with Ansel", then, assuming the players do not replace/skip the opening scene with Lirien, I hope it implies that Lirien has only been having anal sex with Lucien too. That would mean that either:
2A) Lucien is an assman himself.
2B) Lirien is a buttslut who prefers anal.
2C) Lirien is saving her virginity for marriage or whatever and only engages in anal until then.
I hope it's either 2B or 2C... 

 She could then have some extra dialogue / affection for an assman Ansel. To compensate, you could give vaginal/oral preference to other characters, while still leaving Ansel (player) with the final decision of what they'll do,
3) Since you mentioned sex preferences potentially playing a role in combat, I have a very interesting idea. Though again, it's just a suggestion, you can dismiss this if you want.
When we activate Callisdra an intricate tattoo appears on her stomach. So what you could do is - if Ansel sticks it in her anus, instead a "tramp stamp" (A tattoo on the lower back, just above the butt) could appear instead. So then what you could do with this gameplay-wise is:
3.1) Stomach tattoo would mean that vaginal sex with  Callisdra gives stats, while anal is just a bonus for the player, but does not provide any stats.
3.2) Tramp stamp would mean that anal sex with  Callisdra gives stats, while vaginal is just a bonus for the player, but does not provide any stats.
3.3) Regarding oral, it could also give some stats as a neutral option. I was thinking of suggesting an Oral activation, but there's probably no way Ansel could reach her mouth when she's frozen before the activation LOL.
That way you add some "consequence" to the game, making the way we bond with Callisdra more important, but without locking out sex scenes for those that want both vaginal and anal.
Yeah, that's my thinking exactly. If Lucien is supposed to be our main rival, then I cannot wait for the moment when we finally "steal his girl" so to speak. I hope it will be as satisfying as I imagine it to be.