Thank you for this great lore post, I enjoyed it.
Honestly though, it might be simpler than that.
Erden = Earth
Belterre = France; Jeanne is clearly inspired by Joan of Arc, a national hero of France, in fact her actual French name is Jeanne d'Arc, not Joan
Rigland = maybe a blend of England and Germany ("Finn", "von Draclow")
Esma's country reminds me of Thailand, Alira and Gloria's Bergeria is much like Russia, Kisara and some others come a very Japan-like place.
Of course, it's a fantasy world, they are not perfect matches and they shouldn't be. But just like Game of Thrones borrowed different parts of Europe and the world to make its fantasy setting, this game does too.
The religion of the "Radiant One" strongly resembles Christianity, it can be abused like we see in Callen's storyline, or it can redeem as we see in Jeanne's story. It doesn't seem to be a cult, but a world religion.
The Pandemonium hits this Erden over and over again, not sure about multiple worlds.