I think the author should do something to break the routine. It's starting to become a bit formulaic, with the same structure repeated chapter after chapter. Maybe she could focus on their school life? Or add new recurring characters that are not potential romance targets?
Personally, I'd like to see more of their school life, who are the main characters friends, what they do, etc.
I agree with the cast being rather shallow so far, only having gotten Miwa's singular friend on board, but it baffles me to read this statement when we finally get some characters from Yuu's backstory introduced, who might be here to stay. I mean even this chapter foreshadows that someone will (we can go with "might" for arguments' sake) appear in the Director's next "project" assumingly a movie.
It's also clearly set up for the main quartet to experience the budding and potential first blossoming of a relationship, which is another baby-step forward towards a romantic development as we had previously with the whole future "partner" arc.
All I'm saying your complaints are currently being addressed in the very chapter you commented on, at least from how I see it.
As another tidbit, if we do get an acting arc soon, I'm assuming we'll get a glimpse of what Kazukis usual entourage and troupe looks like too, having covered at least 1 arc worth of development for all 3 main girls with their usual social circles.