I have now at long last bought the AR rulebook, and the background in the beginning (the main reason to buy the book since the rest of it is free) is really cool to read. It definitely seems to be the case that "Atlantis" = North America.
I suppose that in the game so far, there are only two Atlantean gladiators - Vargr and Hroka. Right? All the rest of the Zephyri seem Norse. Even Leika, even though she is a bit hard to determine. But I'm not getting much of a Native American vibe from her.
And one Atlantean monster, the Wendigo.