
The reason the mating strategies thread didn't answer those questions is because they are cultural and historical in nature, while that thread only concerns itself with Miqo'te society on a purely biological point of view: an study of Miqo'te as animals, really.
Now, back on topic: I don't see anything lore-breaking in your backstory. The only thing I would point out is that, in Miqo'te tribal societies, the nunh are not traditionally the leaders. They are just the guys that get to have children. So it wouldn't be a nunh who allows Seto and his mother to join the Vulture tribe, but whatever Miqo'te was their chief (or chiefs, if its a council of sorts).
I'd change it to say that the nunh was who vouched for them instead, and the chief(s) agreed with him.
Now, back on topic: I don't see anything lore-breaking in your backstory. The only thing I would point out is that, in Miqo'te tribal societies, the nunh are not traditionally the leaders. They are just the guys that get to have children. So it wouldn't be a nunh who allows Seto and his mother to join the Vulture tribe, but whatever Miqo'te was their chief (or chiefs, if its a council of sorts).
I'd change it to say that the nunh was who vouched for them instead, and the chief(s) agreed with him.