I think I discovered why the Nightsong quest has stuff missing (and her quest ending with "not in the underdark" the moment you set foot in the underdark).
In the datafiles, there is text saying that Shadowheart read a book at the grove that mention a hidden Shar Temple in the area (not in the EA as far as I know). Basically what the Nightsong quest says: under the Selûne Temple. I think the Underground Fort used to be a Shar temple in an older iteration (hence the Sharran Gem now renamed Bloodmoon Gem), but it's now just another part of the Selûne Temple. Her dialogues about having mixed Shar/Selûne statues was probably related to finding that place. It seems everything Shar was moved to the "Ketheric's city" section now. The Harper's note saying the local Selûnites were heretical might be related too (aka old stuff that will probably have to be changed now).
That means a good chunk of Shadowheart story content was moved too I guess. Could explain why she sometimes disappear from the camp, her triggers are broken because stuff were moved as well.
And the Nightsong/Shadowheart confrontation is weird. I think this is old stuff because the narration is in 1st person still in it. I said it before, but the Nightsong seems to have two personalities: one pro-Shar and one anti-Shar...and both shows up in that exchange. She is warning Shadowheart that if she displease Shar too much she will end up cursed like her, but other lines are basically her telling Shadowheart to displease Shar...
Looking at Shadowheart story content, I can't decide if she's going to go totally batshit insane by the end or not. There is only so much conflicting gaslighting someone can process.
