I guess it depends on the naming theme. Dawn and Lucas were themed around light; Hilbert and Hilda was themed after battle.
That's what I'm trying to find out. "Mei" is a type of Asian apricot/plum, and if Kyouhei is the male character's name, then one spelling of "Kyou" can mean apricot as well. So they might have been named after apricot trees. "Hei" means black in Chinese too. Not sure if "Mei" could be used as "white", the closest I've found is it meaning "bright".