Slippery, i agree, I understand it's just common names, so there's no 'official' common name for anything, but people keep giving these misleading names, like the LFS's that list G. tile as snowflake eel.
About FW issue, I think there's enough out there to justify some G. polyuranodon to be in FW, but I personally would be very hesitant to keep a moray in fresh. Plenty of morays venture in to brackish/fresh, even G. fimbriatus...I'm surprised that someone hasn't tried one in FW. that being said, even brackish morays I keep in SW, like im doing with my Strophidon sathete, and my old G. tile