[Suzu]

I think you underestimate the celebrity bonus Koyomi's actress has. She is and already was HUGE in Japan before Wizard, because she's a member of a super-popular girlband (PASSPO☆). She probably signed up thinking it was a minor role or her agency felt it was a good thing to boost her acting career (which she certainly should not follow because that's not quite her talent) or whatever and ended up having more "important" stuff to do, such as model work or band-related stuff.
Since it's mostly her agency that has a word in her schedule, I'm pretty sure they set her priorities and considering that those agencies have pretty strict policies, I don't think Toei could do a lot against that.