Corsanctum should technically be something close to the vatican of SA. But it didn't really work, and the reason is that it lacks the threatening power the vatican had back in medieval times.
More than once Corsanctum's authority was challenged by Morek, after Mathurin was paused, and they couldn't do anything at all. Corsanctum, being quite full of priests and never very successful at expanding, was not truly powerful militarily speaking, and the other theocracies was simply too far to truly threaten Morek even if willing. Moreover, Corsanctum relied on Morek's food and troops to survive for quite a long period of time.
You can RP everything as much as you want, but game mechanics, right now, grant power only to the big states. Little states have nothing to offer that would make their desires listened to.
That power was the power of excommunication, which basicly all catholic nations had execute by removing the excommunicated leader.
You can have all SA realms include that in there oath/treaty to Corsanctum.
It will give corsanctum and the church lots of power.
