I think she's in a horrible situation too. She can't not help her but the way she goes about it is not great either. But then again, how would you go about it in the moment? I think the film very subtly implies that she used to be in a similar situation before, but doesn't dig into it very much.
Elle Maija Tailfeathers is the woman who plays Aila. I googled her after - the tribes she says she's part of in the movie are real and her career has been centered around them. I don't think she is playing the native status. I think what the film gets with this aspect is the colorism that occurs between people of similar backgrounds or races. She's light skinned indigenous whereas Rosie is darkskinned indigenous. What's fascinating, however, is that Aila has a far more "foreign" sounding name whereas Rosie is very much a Eurocentric sounding one.