Okay, first let's make sure there are spoiler tags when discussing plot elements, particularly when it comes to Act 2 and beyond. It's great (in a way) that what happens has had such an impact on the OP, but let's allow others to experience the same by trying to make sure they don't accidentally see what's going to happen before they encounter it in the game.
Second, I also found discovering what happened to the tieflings in Act 2 powerful, moving and in some cases upsetting. Though I didn't go to the lengths of the OP to roleplay this! You have my respect for your commitment
Third, there are certainly things that I think could be done better as the game progresses, and hopefully will be fine-tuned and tightened up as Larian continue to polish the game, but (with the caveat I've still not finished) I've enjoyed having the tiefling's journey as a thread running through my story. Especially as my character is a tiefling herself, albeit from Baldur's Gate rather than Elturel, she has come to have a lot of fellow-feeling for them.
Fourth, my understanding is that communities of tieflings aren't the norm on the Sword Coast, but that having shared the experience of being shunned and exiled from Elturel has brought them together, and unsurprisingly led to a number of them probably giving more weight to that element of their identity as well as a common challenge that it does seem likely would foster a growing sense of solidarity.
Fifth, I disagree with Volourn. I'm not sure how to engage any more constructively than that without sending us off on a tangent!
