Yes, I think this would be a simple fix to do, since our character isn't voiced. I don't understand why they haven't done it yet, honestly. It could be as simple as adding a short animation of our character running after Astarion. If changing the order of scenes is impossible, our character could say some line showing concern and an animation making the move to go after him, but Karlach dying draws our attention and stop us.
I don't know. Being our romance, it feels weird that our character prioritizes Karlach when he is also in mortal danger and we don't know if he is ok. Even weirder is the possibility of being able to go with Karlach to Avernus and abandon Astarion to his fate. I love Karlach to the moon and back, but this doesn't make any sense and in this aspect, the romance with Spawn Astarion feels neglected.
