Rag, I'm not trans so I can't give the best answer to your question but for my general thoughts on the matter... it's complicated. Personally when it comes to the various -isms, my opinion is that a property shouldn't include it 'just because' or for the sake of a nebulous idea of realism. I'm of the opinion that for games in partcular, the best bet is probably to ere on the side of inclusivity unless it breaks the setting or story in some significant way. I think that if you're going to have isms in a game, then the game should address them in some way, they should serve some narrative or setting purpose. Obviously there are degrees of this, but it's in my opinion, a rule of thumb that's probably a good approach.
As you say, for some people playing characters whose gender identity doesn't match their gender presentation, being repeatedly misgendered and having to correct others would be frustrating. Hell, I'd venture to guess that MOST players would find that frustrating purely because it's a tedious chore taking away from the point of the story. And while that could be an interesting way of putting cis players in the shoes of trans people with regard to that particular lived experience, I think it's not worth it for a game that's not really trying to be about weighty real world issues in that way. Obviously if the game wants to actually say something about heavy issues then it's free to do so, but if it's not trying to say anything, then I don't think those things actually improve the work. Game of Thrones works with all its violence and abuse, inequality, etc because fundamentally its a story about power, what it does to people who have it, how far people are willing to go to get it, etc. So things like rape, slavery, racism, etc belong there as it all contributes to those themes, the conflicts of power and powerlessness and the horrors absolute power brings. In dragon age: Origins, the city elf origin involves a bunch of lords kidnapping elven women to rape and probably kill. That story fits because it's part of the tapestry of elven subjugation and abuse, an aspect of the worldbuilding that the game actively engages with repeatedly and unapologetically. A plot point like that in BG3 would feel gratuitous and out of place because it's thus far, not a game that's trying to thoughtfully engage with such topics.
So I think that while there's stuff to clear up and improve with Larian's implementation, I don't think going too far in-depth with regard to 'realistic' reactions would ultimately be in the game's best interests. It might even come off as a bit arbitrary, since you can play any race (in the real world idea of the word) and you can play as a man or woman without dealing with realistic prejudices that occur in our world either.
