Same issue here. I usually find it later when I'm looking for empty rooms for newly-joined nobles. Or I am looking for one specific noble's room, and come across the dead one's room.
I've started to color the beds yellow if they are taken, green if they are open, and red for the leader. But I still forget to do that when I unassign a dead noble, too. So it usually is up to chance that I find them and change the owner manually.
Same issue here. I usually find it later when I'm looking for empty rooms for newly-joined nobles. Or I am looking for one specific noble's room, and come across the dead one's room.
I've started to color the beds yellow if they are taken, green if they are open, and red for the leader. But I still forget to do that when I unassign a dead noble, too. So it usually is up to chance that I find them and change the owner manually.