I mean, if anything Michiko and Randa (and Pesca, i forget her real name) are the mid-season reinforcements for Tres Magia, rather than any antagonistic force.
This is, again, that loving deconstruction at work.
Every Lawful Good magical girl team needs a Chaotic Good, just this side of Neutral, team as a foil that they clash with over ways and means despite the fact that they're fighting against the same villain.
Sometimes you get the first four members, and then number 5 is the Chaotic Neutral, in which case they're also a Lone Wolf™, sometimes literally if the magical girls are animal themed at all. Sometimes it's an entire mirror team, like the Outer Sailor Senshi. Occasionally, you have to have one member of the Lawful Good team corrupted by Dark Energy🄫.
Regardless, the author is showing nothing but the absolute most degenerate kind of love towards Magical Girls.