Like I said, this is absolutely not anything I think is a mistake on your part - so it’s okay if it’s difficult/impossible to implement or hard to understand. I appreciate that you’re willing to try.
I can only speak for myself in terms of what I find acceptable, but here are some word suggestions (others may find these off-putting):
Vagina/pussy: hole, front hole, cunt (some may not like this one), boypussy/boycunt (another that some may dislike), man cave (kind of hokey)
Pussy lips/slit: lips, folds, vulva (might be too anatomical-sounding?)
Clit/bean: dick/cock, t-dick/cock, dicklet (can be used to humiliate also, if that’s relevant), nub (kind of vague but gets the job done)
For terms referring to a trans woman’s genitals, I can’t say what a trans woman might prefer since I’m not one, but here are some terms I’ve read online:
Penis/dick/cock: dick/cock (some trans women don’t care about terms that much), shaft, strap, girldick/girlcock, clit, member, hen (like a cock but for a girl lol, uncommon but catching on a bit), venus (penis but with a V, also uncommon)
Tip/head: I’m not sure if there is a specific term that trans women might prefer for this part, tbh
Balls: Again, another one I’m not sure of, but I’ve read people online sometimes use “orbs”; more info/opinions from trans women are probably needed
In general, I’ve also read that a lot of people use the words “bits” or “junk” to refer to essentially any aspect of their genitals, but that seems a bit non-specific for an erotic role-playing game.
Regarding your question: “Does this dysphoria also include when a character is talking about their own body parts? Or just the pov situation?” I would say yes - it’s pretty difficult for me to refer to my own body using conventional terms, even through text.
I totally get that this may not be possible/practical for you to do! That’s totally okay, I’m fine with a game not being tailored to me - they are a lot of work to make and you’re a solo dev. Again, I really appreciate your efforts to understand and see if this is workable. Thank you for having an open mind.