I'm not sure what kind of redemption arc you are envisioning, but Komaki is not this antihero with blood on her hands who has to turn over a new leaf to win the affections of a love interest. Wakaba is already in love with Komaki, so all the latter has to do for a happy ending is stop being a coward.
I mean, she’s a manipulator whose forcing things on another girl and consistently demeaning and belittling her, along with intentionally stealing her crush. She’s kinda super shitty as a person if you look strictly at her actions. No amount of gay pining makes it acceptable, that’s a horrible way to treat someone you care about and entirely too toxic to build a relationship on. She’s also CLEARLY painted as the villain in the story that the hero is trying to “beat”. Having a sad backstory is just fluff.
A proper redemption arc requires a Fall From Grace (losing something important as a direct result of their negative behaviors or actions, importantly NOT due to circumstances), Realization (understanding and reflecting on those negative behaviors or actions), Improvement (making a dedicated effort to change) and Apology (making an sincere effort to honestly apologize without any expectations from the hurt party). Only after that should a character be offered redemption (but not guaranteed). For Komaki it should be something drastic such as her behaviors being exposed and becoming a social outcast, or having someone else take one of Wakabe’s firsts.