Didn't Sailor Stars originally plan on using an anime-original outfit for Usagi, before deciding to go with the manga's Eternal look? I think that outfit had a French name or something.
That’s correct! Although as far as I know, the design was never given a name. It’s known informally by fans as “Fukano Moon.” The name comes from Youichi Fukano, an illustrator and character designer who worked on Sailor Moon and designed Sailor Moon’s potential look.
(second image comes from Three Lights, who has scans of a number of Fukano’s other works as well)
Personally, I think the design is absolutely beautiful and I love how it incorporates elements of both Eternal Sailor Moon and Neo-Queen Serenity’s designs. I think it would have acted as a cool bridge between Usagi’s Sailor Moon and Neo-Queen Serenity forms. Oh well, I still like Eternal Sailor Moon’s design.
EDIT: This design was actually called "Sailor Moon La Cygne" or "Sailor Moon Swan"!