Story-wise, I made Shart reject Shar, then I (unintentionally lol) skipped the Scientology confession ritual and went straight to meet and kill Viconia before ever seeing Nocturne. That may be relevant for the various flags involved.
Disclaimer 1: it could be the fault of my modlist, but OIO and/or Really Shadowheart should be the only ones that touch dialogue, and they're both higher in the load list. I also tried disabling them and reloading and it didn't change anything.
Disclaimer 2: I upgraded from NA 5.x to NA 6 mid-playthrough, while I was in Act 3. I overwrote all the 5.x files with the 6.0 new ones (including DialogTree.pak); the upgrade was otherwise flawless, including Ser Aylin becoming Ser Aelen. So if that could have messed things up, my fault.
* The voice in the nocturne.mkv file linked in the OP was much better, IMO. Did that change?

