I can see a bit of an issue with making it a quest though. Logistically that is. Who owns a burned castle if it’s been rebuilt? What’s to stop a player from letting many keeps be destroyed to rebuild them for a specific faction? If the faction that owned the castle before it was destroyed is hostile, does the quest never occur? Granted, if they’re hostile chances are the location was never used to begin with, but relations do change over the course of a game. A down castle absolutely changes patrol generation which makes roads immediately more dangerous. Castles and settlements definitely need to be restored, but whether that’s from a quest, event, or other mechanism is up in the air.
The owner should be the faction who owned it before, now if the faction is hostile you should probably wait for it to become neutral or unfriendly to do the rebuilding. As for the quests, and that isn’t a reply to Sekata, I don’t believe they should require a specific background brother, like a woodcutter or a mason. After all, we command a mercenary company whose main purpose is to fight, not to build anything. Therefore, it should provide protection for the peasants who seek to rebuild the town, perhaps in quests similar to that in the Undead Invasion when you need to defend a city from the incoming hordes.