Ngl i think some of it does have to do with popularity but that just leaves medusa and eresh fans eating dust and overdosing on copium

Some are based on previous summer CEs: Helena, Carmilla, Okki, Murasaki, Musashi, Jeanne, Sei, Abby, Hokusai. Some are directly related to or loose related (by region) based on the Malee CEs: Buunytoria for Roundtable Knights and Arthur CEs, Bryn for Sigurd CE.

I think they just throw a dice and raise the middle finger to Eresh and Medusa fans.