Hebikawa "winning", to me, means she figures out that her initial goal of "proving 'darkness' exists inside perfect characters like Kusunoki" isn't worth doing.
My guess is, she has a not-good home life (divorced parents, relationship with dad isn't good), and after finding out as a child about that "perfect idol" on TV having a secret dark side, she projects the trauma-adjacent childhood she had onto those she sees as having a better life, thinking "surely they don't actually have it good, because what would that make me and my situation?"
I might be incorrect, but that's how I've always read her character, and her stated goal of trying to make Kusunoki "fall" -- basically, adolescent jealousy.
So if I am correct, then I hope she finds that she has the power to choose a better life for herself, that doesn't involve tearing down/exposing false secrets of those around her. And I think Keisuke is the key to that, because he's shown her in this very chapter that he could change in a way that seemed like an improvement on his past self--namely, he can now look her in the face without feeling violently ill after what he was put through because of her back in middle school.
By hanging out with him, I'm thinking Hebikawa learns to mellow out, that she can build real relationships and friendships of actual substance that aren't the more superficial side that you often get in adolescent "popularity-based" groupings, like her current clique seems to be. And in doing so, she'll find that she can choose her friends, her supports, and learn to let go of those feelings of jealousy and self-inadequacy and that it's not that other "perfect people" are fake, but that everyone struggles, and it's neither a contest nor cause for either pity, doubt, malice, or whathaveyou.
So...learning empathy, I guess, which is important for everyone to do and does take time and lived experience and stepping out of your comfort zone.
Hebikawa's my favorite character of this series, but I don't necessarily want her to get with Keisuke in a romantic fashion. But I think they would be important friends to the other, because of their disparate perspectives, but also because they could help one another grow (Keisuke already has, in terms of resilience, thanks to Hebikawa--and he's helped her already on more than one occasion in some fashion or another).
If she does manage that shift in her character (assuming I'm correct on what drives her in general), I think that'd be an objective win for her arc.