aquamarin said:
The current ordering makes no sense for people trying to find her art because nobody refers to her comfy outfit as her 5th. We usually call it "3.0". And I doubt Miori herself considers 3rd and 4th (chibi) as a full fledged costume.
The best way to make these costume tags useful is either using what Miori and her fans call them ("1.0", "2.0", etc.) or descriptive names that also help non-fans.
We generally try to avoid fragmenting costume ordering because that had a chance of causing its own sort of confusion. It's why we don't distinguish 2D and 3D only costumes for a bunch of VTubers, and I don't see why this wouldn't apply in this case too, given the fact that the chibis have their own unique outfits rather than just being chibified versions of her regular attire.
Regardless of that, it wouldn't be too difficult to make utility aliases which direct miori_celesta_(miori_1.0) to her 1st costume, ...miori_2.0) to her 2nd, ...miori_3.0) to her 5th, ...miori_4.0) to her 6th costume, irrespective of the ordering on Danbooru, if you'd like to make it even more accessible for fellow guildmates.