Why do Haurchefant, Estinien and Yugiri have Hyuran last name?

[Valenth]

Apparently it's not uncommon for Au Ra to take on more Eorzean names when wandering away from Doma (or at least in Xaela's case). I figure this is them taking on the Eorzean version of their original Doman names.

Edit: I based my Au Ra's name, Valenth Guiran, on the fact he took on a more Hyuran name for the sake of blending in better, but that originally he has a (yet to be determined) Doman name. Well, actually there is a bit more to his story, but I need to flesh it out at some point as it's all still vaguely in my head. It involves a phial of Fantasia and people needing to think his original is dead. :P