Resurrection level healing: Not sure I understand the question.If resurrection level healing saves somebody struck by their immortality flaw before they die, do they need to redo their immortality? My gut says yes. Same for new resurrectees.They need to redo their immortality too. Not sure on current implications of that approach.
War disconnection by fount:
Alchemy: Unkillable barring rube goldbergian coincidence nobody intentionally set into motion. If by some miracle that happens they lose immortality but don't otherwise die. Alternatively, any attempt to brew their immortality counter agent is doomed to fail.
Arete: Unkillable. Immortality flaw requires volition. Hair garrotes fail. Clone assassins fail. Even if an attack stripped their immortality it would never make contact.
Elementalism: They bounce off an invisible wall at the edge of the Basin, surviving unharmed wherever they get bounced. One disconnected elementalist (bound and gagged because reasons) on a spacecraft in space makes it impossible for anybody to commit catastrophic sabatoge against the ship.Cannons on enemy ships will miss it. Airlocks refuse to admit the elementalist. While the disconnected one can have no knowledge of or participation in such schemes, it enables highly effective usage of spaceships as projectiles if it can be pulled off. Alternatively, being spaced neutralizes the disconnected ones restraints instananeously.
Oneiromancy:: Unkillable barring rube goldbergian coincidence nobody intentionally set into motion. If by some miracle that happens they lose immortality but don't otherwise die.
Necromancy: Unkillable barring rube goldbergian coincidence nobody intentionally set into motion. If by some miracle that happens they lose immortality but don't otherwise die.
Invocation: Unkillable. The necessities of the ritual are impossible to perform.
Earthpower: The proverbial mistletoe dart won't work. Unkillable barring rube goldbergian coincidence nobody intentionally set into motion. If by some miracle that happens they lose immortality but don't otherwise die.
Unruly Lands: I guess it depends on the tradition. If 4-5 can be reached by having difficult to make, infrastructure requiring magic items on your person, or needs bleeding edge augmentation medical facilities, they need infrastructure.
If the tradition is inherently friendly to magical self augmentation, sufficiently so that people can bootstrap themselves to 4 and 5 if they were lucky enough to find the right reagents for example(Which here I'm basically using as code for Xianxia style cultivation drugs, if you look at some of the fount principles, spiritual distillation and refinement in necromancy for example, there is some compatibility with Xianxia concepts there ) without large scale infrastructure that's a potential explanation for low infrastructure unruly landers with 4s and 5s.