Why were 3 of the Witches 5 given so little screen time? In the first anime Viluy, Tellu and Cyrpine were given so little screen time and they were used as one episode guest stars. But Eudial and Mimete had longer story arcs. How come?

This is only speculation and not confirmed information, but the only reason I can think of is bad Episode-Management. After Eudial's and Mimete's Story Arc they realized that the season's end was near and that using all Witches 5 would mean prolonging it. Because this would also mean more filler which would possibly mean fewer views, they just gave each of them one episode instead of skipping them altogether.

^I never even considered that! O:

It also helps to note that each of the witches five in the manga only lasted one battle/chapter in the manga.

I would say that they gave Eudial and Mimete more screen time than the others to stretch out the story. It would have been like Crystal if they gave all 6 witches their own episode in the 90s anime or the season would have been too long.

My personal theory is that it has to do with production pacing. The anime and the manga were being actively worked on at roughly the same time. It takes a while to produce an episode of anime, so they couldn't necessarily wait until the last minute to work on the episode while waiting for information from the manga storyline. I think it's likely that the anime team simply had more advance knowledge of Eudial and Mimete, so they created episodes based on that planning.

The same sort of thing happens in the SuperS season, with the Amazon Trio getting a lot of episodes despite being one-shot monsters in the manga. I suspect the anime team worked with what they were given about the overall plot at the time they were given it.

from moonsticks.org