A bit of a suggestion regarding religion namely sedevacantists. I think it would make sense that they would have large numbers of adherents in Mexico, Central, and South America. For example 60% of the provinces in Mexico would be sedevacantists but would be ruled by nobility all of which are members of Sagrado Corazon or the other religions of the region.
The same would also be true in the Christian regions of Canada and a much smaller percentage in the lands loyal to the St. Louis Papacy.
The Sedevacantist holy places certainly shouldn't be the same as the St. Louis holy places because why would they have any connection to any of those lands? Their holy places should be places/counties like Mexico City where the basilica of Guadalupe is, Quebec in Canada, San Diego, Los Angeles, and some other historical Catholic location near either Quebec or Mexico for balancing. If it were possible to have more than five holy places then I would suggest to add a few scattered in regions like Cuba and South America.
Another idea is that once a sedevacantist holds at least four holy places and an empire title plus one holy place of the St. Louis papacy, a decision could be opened to mend the schism (similar to Orthodoxy in vanilla). Mending the schism would change the name of sedevacantism into Catholic and reduce Catholic (St. Louis papacy) into an antipapacy within the newly formed Catholic. After mending the schism Catholic would instead of having a Pope (because sedevacantists have no contact with Old Rome) would have archbishops in each controlled holy place.
With four fully converted holy places the archbishops can decide with a simple majority(3/4) to excommunicate, call a crusade and all other powers Catholic normally has. The emperor could ask for them to decide on an excommunication or crusade on a specific nation/person. There is an incentive to getting all five holy places because the simple majority vote becomes easier to obtain (3/5). (A bit strong, yes but a good reward for accomplishing this feat, since the holy places would be rather far apart)
Any thoughts? I just really thought it rather strange and immersion breaking for all of Hispanic America to have fallen to pagan, saint cults, and native religions without so much as some resistance. French Canada as well, does anyone really expect the Quebecois to simply lay down in the face of a female clergy? I think not.
May religious revolts plague the future of these regions. I beseech ye mod devs! Bring immersive immersioness onto we the unwashed wretches!