The more I think of it, I just wonder if balancing the "role" numbers isn't really a thing.

A pattern holds better with theming an expansion's area with it's jobs. Look at Dark Knight, Machinist, and Astro being important in Ishgard with Heavensward. Red Mages coming from Ala Mhigo, Sams from Doma and Kugane for Stormblood. Gunbreakers from Bozja with Shadowbringers. Reapers from Garlemald and Sages from Sharlayan in Endwalker.

The only class that didn't get shoe horned in the right expansion was Dancer being from Thavnair. And it was the most requested class and it's lore area literally followed the next expansion. Which makes the counterargument weak.

I think if they move 7.0 to Hingashi we'll see Geomancer. If in Corvos we'll see Mystic/Rune Knight. Ranger or Shaman with the New World or Mercaydia. Viking or Valkyrie with the Blindfrost. Corsair with the South Sea Isles.

TL/DR: Role balance numbers don't matter; lore expansion does.