I don't agree with Bralbaard's worries that a fort would attract invasions more than usual, since we've seen in 707-708 the elf capital was sacked without any player interference or fault, which to me means that enemy civilizations do not target settlements based on them having been a player fort or not.
That being said, I do worry about other technical issues should a fort be built on top of Boltspumpkin. That being said, me building a fort on top two NPC towns so far has not resulted in any problems. If built, the fortress should probably never be unretired, because that once again causes all sorts of technical issues (item scattering, items dumped out of bins etc.).
I tried unretire-anyone on Rope Mobbedwilt, and she is hanging out in Championvault. Not sure why she hasn't been summoned to Boltspumpkin.
In that vein, there were some dwarves who ascended to Barons and simply refused to leave for the capital. I don't know if the behavior is random, tied to something random (i.e. dwarf has weapon on, dwarf is hauling etc.) or if they're smart enough to realize the massacres happening in Ilrallenod and not wanting to be part of that.
Ah, when it comes to "outcast"/bandit groups, I think most ascended leaders remain in the town they lived in. For example,
Kem Kilaura should have probably moved to Odiuse once he ascended as the leader of the large outcast group, but remained in Mabkor.
In contrast, Ngokang left because Avolition freed him, which I suspected messed up his AI pathing (around the world).