I've noticed that despite the additions of new dialogue here and there and some smoothing, they haven't actually changed the base game to any real degree. They've added things certainly, with the epilogues and now Minthara for good playthroughs and companion reactivity etc. But no new quests have been added, the story beats are the same, and the game still goes the way it goes.
Which is striking because the game has lots of plot holes. Karlach is arguably not even the most egregious. The ending is still a mess, lots of quests are still strangely paced, and there are still dangling plot threads. I'm guessing that IF they add a fix for Karlach in game (and that if gets bigger after the epilogues are out), it'll come when Act 3 gets smoothed over for the DE. Frankly, I'm okay with what we got. All I really wanted was to know that everything was going to be okay for Karlach and Tav, and things seem to be quite okay thank you very much.