In the end, it comes down to how much you (and your group) want to hold to the mythology of the DF setting as designed by JB.
Harry states several times in the books that Faerie inhabits the parts of the Nevernever closest to our reality, and is inhabited by those beings with the strongest ties/interests in our world. I'd say there's evidence that any faerie-like beings from other folklore traditions are actually treated as faeries, with the same weaknesses, based on Harry's comments about the Svartalf smiths, and how much he had to pay them to work with iron in forging his new summoning circle,
in Changes. Also, I believe Harry used steel barbed-wire to make the circle he used to summon and bind the Erlking, specifically because it was "cold iron," and thus added another level of symbolic restraint. So far, it seems that only ghosts, gods, angels and demons (and Outsiders) are the only beings from the Nevernever to appear in the Books so far, which do not have Faerie weaknesses.
Having said that, there's no reason why anyone's game must adhere to these conventions.