I think Sam actually mentioned this to an extent during one of their interviews. Saying that Karlach is very much living in the moment but also ignoring her trauma/problem. Playing as well, non-Karlach, you only somewhat see it because it really only gets brought up after you give a second piece of infernal iron to Dammon, and during a bit of act 3 after the date or after Gortash. She finally gets some good news and doesn't want it spoiled by what Dammon says, and then ofcourse it all comes crashing down after Gortash. It's REALLY sad, and any attempt to offer a solution like Avernus is immediately shut down. Which, is understandable, it's hell and enslavement/conscription, but the reality is that the only chance to fix the problem is to go back to hell to find a solution.
I still don't think that sits very well, where it's "I don't want to face that 10 year trauma so I'd rather die" because it feels like 2 ends of an extreme. It's why I keep flipflopping between what ending I prefer, because it's impossible to offer Avernus where you fight for her without it getting shutdown. Until she is literally about to explode. Simultaneously, it's also why I kind of dislike the Avernus ending because it feels like such a sudden shift. Where she's ready to fight as hard as possible, shows no fear and is gonna ruin Zariel. I think my most recent playthrough that's got to Act 3 was done mostly before Patch 2 so I think I missed a lot more of the build up for the tug of war of her emotions, so maybe that's a mute point. But it does feel really jarring to me, like you said.
