Frankly, no idea. I am not seeing this issue myself, and non-pagan Hungarian female definition hasn't been changed since when Reaper's Due came out last summer, so if there was anything wrong with it I'm sure there would have been bug reports about it.Any idea whats going on here?
The weird thing about the missing hair texture here, though, is that non-pagan Hungarian hairs are loaded up directly from vanilla. Could you check if other Hungarian characters and French and Norman characters are having similar issues? More details help.
Lastly, in your CK2 folder, are gfx/characters/western_male and /western_female missing files that have "hair" in their title by any chance? (e.g. western_female_hair_behind.dds) If so, assuming you are playing CK2 through Steam, check the integrity of your CK2 and you should have those files back.