A suggestion in trying to get one’s mind around Gloranthan cults, kingdoms, and empires – loyalty is usually personal and not ideological. I might have a tremendous loyalty to my local leader or kinship group, but that is personalized. If my loyalty is to Leika, I don’t necessarily have any loyalty to her successor. I might have a lot of loyalty to the Colymar, but if the nearby Cinsina tribe suffers I am likely to shrug.
Same thing is true within cults. I might be loyal to my local temple, but not to some distant temple to the same god. I might be devoted to my god, but ignore his priests.
Personalize things, rather than use the lens of abstract ideology.
As a result, Gloranthan societies tend to be far more heterogeneous than we often give credit for. People end up with seemingly unthinkable alliances far more often than we might assume. And personal loyalty usually is more reliable than ideology or abstract principles.
Loyalty to Sartar usually is expressed through personal loyalty to the Sartar dynasty, and not to some commonwealth of tribes.