I'm sorry to disappoint you then. Nothing is absolutely permanent in the game, except some things where you have to make that explicit choice.
Don't get me wrong, this game has so much quality it's insane. It's mostly just a me issue I guess, since I had the same problem with Darkest Dungeon; because it's kind of The Point of each game, though, how can I really complain when it's very clearly advertised?
The in-game encyclopedia is pretty comprehensive, but I'm still not sure how you get rid of undesired crests, which seems to be the most major thing that happens when someone gets kidnapped. Maybe it's a skill issue that 3 of my most useful characters got kidnapped so early on, but it's very stress inducing for me knowing that I have to wait until they're put further and further into a utility hole in order to let the difficulty lower enough to be capable of rescue. It's almost worse than them just dying like in Darkest Dungeon since if they were just dead, then I would have to move on or give up instead of putting more time and resources into trying to rescue and fix them.
I don't know if there's a solution to this other than just sucking it up or not playing the game (I don't expect the game to be so radically changed just for me), so IDK why I'm even saying all this, I guess I just wanted to express my frustration, get it off my chest.
Again, it seems like a great game overall! Really looking forward to the cow and parasite stuff when I can finally claw my way back to a normal-ish state so I can actually make progress in the game and interact with the parts of it I want to!