well done on almost finishing your first run
Almost?

What did I miss? Does it only “count” if you don’t use Gale at the end? If so, then also don’t talk any of the Thorms into ending themselves, and basically never use charisma to resolve and avoid any potential combat encounter…
Then it was Cazador and his gang of undead. He tried to transpose Astarions wisp (which I think will perma-kill Astarion from the game, he is dead-dead if he gets the spell off!) to the holding cell and Gale counterspelled it.
Wow, I didn’t even know Cazador could do that again after the cutscene. He never tried to in any of my playthroughs.
As for Astarion being permanently dead if his wisp gets imprisoned, I would hope you can target the wisp again once Cazador is defeated? As all the other spawn are released at that moment, too.
Of course, it might as well be like when a character dies on Orin’s altar, which is permanent. I think the kidnapped character even retains that permadeath risk until the next long rest, so I’d always Long rest immediately after the Orin fight (or at least not take the kidnapped character out of camp before the next long rest).