I believe Swen said in an interview recently that they're working on new endings/epilogues and doing content updates, although he didn't mention fixing Karlach's ending specifically. Larian doesn't usually publicize what they're working on until it's ready to go.
They definitely know that the matter isn't settled with the community though, Justice for Karlach is on the list of frequently requested feedback on the Larian discord server and there's still new feedback threads popping up about it. Between that and this rapidly becoming the largest post on the forums right now I think they're pretty well aware that we aren't happy.
Yeah, the Patch 2 Karlach addition marks the first time Larian has actually gone out of their way to say they're going to do something like that before they do it (Addressing Minthara as well, congrats Minthara fans). Fane from DOS2 wasn't touched until 10 months later in Definitive Edition with a similar "bad or worse" ending scenario.
As much as Larian has hurt my trust with Patch 2, I'm glad that they at least RECOGNIZED the issue, and hopefully that means along the line, with time and work we'll see an actual large addition to Karlach in the form of a real good ending, and fleshed out story. Time and patience is the game.
