It feels weird, the Mc is losing too much screen time at the start where the Mc needs to hog at least 99% of screen time, if that fails to happen then that's bad writing, and if Rikka is the main character then the cover showing Winnie, basically makes the cover a bait, you would expecr a depressed magical girl past her prime slowly gaining back her !MOTIVATION! as she outshines her past leader, that would be what the cover would suggest to us the reader, and not family drama of a side character.