There seems to be some minor confusion surrounding how to tag the images filed under Neptune_(series). Case in point, there are a lot of images under adult_neptune wrongly tagged with neptune_(choujigen_game_neptune). Also, there are a lot of images that use choujigen_game_neptune as the blanket tag for the series as opposed to neptune_(series) though I may be wrong on that mark. I'll work it out when I'm done fixing the adult_neptune neptune_(choujigen_game_neptune) problem. Any help is appreciated.

Adult Nep and Nep-Nep are techincally counterparts to one another since Adult Nep is Nep-Nep's Ultradimension self without CPU powers but the two are pretty distinctive towards one another that I have no problems keeping those two tags separate from one another.

I'd like some help on their transformed forms too.

Generally their names are used interchangeably, if only at the start: When the girls first introduces themselves they call themselves by their transformed names (*** Heart) and then give their own names, regardless of their current form.
In VII the text box refers to them as "*** Heart (Name)", reinforcing that they're alternate forms of that character.
In 4GO the Goddesses are separate NPCs, characters unrelated from their human forms, and neither can transform in each other.

Despite the first point, my opinion is that they should be tagged only by their current forms (tag what you see), because when you're searching for their human forms you don't want the "unrelated" 4GO Goddess form that was tagged with their names to appear. I've seem Next forms tagged with all 3 forms names too, which just makes it worse.