"Regional," in this case, likely applies to Gyr Abania / Ala Mhigo. The intent is to make it seem like the Imperials are saying "Well, webrutally subjugatedconquered your homeland and are yourdictatorsgovernors now, but we're letting you keepa mockery of an aspect ofyour culture! We're not so bad, see?"
Either way, Gyr Abania was not the first place outside of Ilsabard that Garlemald conquered. That "honor" goes to Dalmasca, which was "easily" taken with the Imperial airship fleet, as I recall. Next went Doma, and then Ala Mhigo... I think.