Hmmmmm, I don't think it's due to any code errors, since I copied the code from PBA to every other file and just replaced the type of building the quest chooses and the type of npc it spawns inside, so the syntaxis is pretty much the same. But I guss I'll post the files just in case someone wants to give them a look.
That's... really weird, because both PBMASTER and PBA are inside /StreamingAssets/Questpacks/Populatedbuildings, so I shouldn't have been able to start them from the console at all and it still worked. I really have no idea what's going on here.
EDIT: I just moved the rest of the files to /StreamingAssets/Quests and tried to start them using the console and I still got the "Quest ID 'PBB' could not be found" message, so I doubt the file folder is the reason why the console can't start them. I also tried to start some quests from my thieves guild questpack from the console and it worked, so it seems like startquest can actually start quests inside the questpacks folder.
EDIT 2: I rewrote everything except for PBA and it seems to be working alright now. Idk what happened honestly, must have fucked something up when copypasting it or something