The thing is, the village of Miramanee must have been the planetary capital, due to being the only one with an obelisk. But do we actually see any signs of the related interaction with lesser settlements? I mean, there have been repeated signs from the heavens "since the last harvest", yet there aren't concerned envoys from faraway settlements in evidence when the Elders meet.*
Spock sees e.g. Mohican characteristics in a settlement that must be absolutely static and non-nomadic; so perhaps what he sees does not include major, characteristic things like inter-tribal trade, but rather minor and incidental things such as dressing code?
Overall, the idea of a single settlement being the mixture of the three cultures listed would speak of a fundamental change in all three cultures, would it not? Unless Spock were seeing traders from two cultures visiting a third, but it doesn't sound like that at all.
* The signs were basically global, involving darkening skies. If those were other asteroids zooming past, were they clean misses - or does this mean the planet has more deflectors elsewhere, implying other settlements that refuse to talk with this one on obelisk issues? Or were the darkenings just artifacts created by the obelisk to summon the Medicine Man to the controls? The issue is incredibly muddled: apparently, the deflector requires manual control, but nobody alive knows how to operate it. Evidently, the obelisk will teach the necessary skills when needed, but this calls for the student to enter the obelisk, and nobody knows enough to do that, either. "Legends" tell of previous asteroid encounters, but as Christopher
says, these people have only been here for a couple of centuries - why are their memories so piss-poor?