It is entirely irrelevent whether you are working off an existing IP or making your own, in fact, you'd have more leeway with an existing IP because you would be expected to make a parody of it, (in the adult games sphere anyway).
No, you should not just 'change the lore to make it more viable,' It is more important to care about the work, the worldbuilding and the story than trying to maximise profits to keep everyone happy.
My point still stands, once you establish lore you stick to it, or things simply don't matter.
And this game is an RPG, it's open for anyone to play, and will allow for as much choice and experience for players to choose as they want.
You get the experience you want playing the game, if you don't want futas, simply don't pursue them and romance the many, many women available ... But leave others to choose what their adventures will look like.
I won't address the matter any further.