I get where you’re coming from, but it’s meant to be a magical thing not a reference to real-life intersex people (or any real-life people), and those terms wouldn’t likely apply in this situation. I also don’t think it’s okay to call real people anything like “futanari” the same way I don’t think it’s okay to call a woman “slutty” even though that happens in this game since that’s part of (IMO) the kinkiness of it. That said, I also don’t feel the term when used neutrally to describe a specific type of fictional character can be fairly considered a slur at all.
Also, this game fetishizes a lot of things. It is porn after all. Again, if it is offensive to you, I hope you know that’s not my intention and I am open to hearing suggestions on how to fix it, but I also don’t think I’m using the term inappropriately or in an offensive manner. But I also get it if it’s upsetting. I still cringe internally when Frieza in DBZ calls Saiyans “monkeys,” lol. If this were a realistic/non-fantasy game and I was referring to trans or intersex characters as “futanari” I’d agree that that’s problematic, too, so I’m not trying to me dismissive of your concern. I just think in this case the term futanari is actually accurate. I could invent a whole new term, but then people wouldn’t know what I was talking about and people who are into this kind of content might not even realize it’s in the game.