The treaty under which a lot of those claims were laid out does not allow Caerwyn nobles to take claims like that. It also did not allow Itaulond to lay claim, as Caerwyn never ceded claim to them. The only way that any realm could make a claim to the land was by making up a new way to do it. At least insofar as any pre-existing document goes. Astrum claimed right of conquest, Terran claimed that the lands were never occupied by Caerwyn, so Astrum could not have been said to have conquered them, and claimed them as "they're close to us, so they're ours". Asylon never really tried to claim farther than the Via duchy by possession, and no one cared to dispute the claim to Via.
