One damn crusade in one pisspot little backwater civil war.
The church has literally not done squat besides that in the years Hireshmont has been part of it.
That it's a pisspot little backwater civil war is probably precisely why it was so bad. Everything was wrong about that crusade. The "enemy" had astroists, no astroists were being persecuted, the territories weren't worth anything to the church, the realm defended wasn't viable on its own, it was ingerence from northern realms in maroccidental affairs, it was slapping a foreign type of governance into republican territories, it was forcing a whole bunch of people to do stuff they didn't want to do when they had a ton of more important things to do, etc...
If the war had at least been meaningful, then people would have been ready to make concessions. But it wasn't. Whether it was the case or not, it had all the appearances of being the direct result of a corrupt eldership abusing of their authority to declare crusades out of spite from certain individuals not fostering the interests of the Church in mind.
There wasn't really any way to oppose the previous crusades, for the targets were always going out of their way to assure their own destruction. But Phantaria did not. And between them, came Rabisu's firm refusal to call for a crusade against Aurvandil, despite all of the astroist realms pretty much lining up against them. You really could not follow the refusal of a crusade against a state that totally deserves it with the imposition of a crusade against a state that clearly doesn't.
Basically, Vellos assured SA the same fate as Terran. Rotating between soft and hard and soft and hard will just break the church. It needs consistency to keep everyone on the same page.
Because of your last crusade, you next one is likely to result in your humiliation. Niselur, Farronite Republic, Asylon, and Phantaria surround Astrum. Libero Empire and Luria Nova flank Morek.
The days of the theocracies are over. SA will have to learn to live through the republics and monarchies of the land. And indeed, it's likely going to lose a lot of the power that made it unique. But what can be done, you've already destroyed the authority that granted them this power.