Okay, this is really odd. I definitely only had like one or two of these shoes back then. And oh, you didn't have to upgrade Mana's photo. I only really use it for its skill.
Honestly, I'm not sure what seems to be problem here. You have far better accessories and higher levels than what I had when I did it. Sorry that I can't help. But just maybe, it might be your photos. I think you probably have 4* films now so maybe try taking more photos and hope that you get lucky with high rarity and quality photos. I really don't think photos are the problem though. There is an option of just using scorers to win by sheer stats but I don't think it works here since there aren't that many dance 5* scorers.
And I've heard that the event only accounts for the level you were on when the event started so there's no point in trying to rush after all. Its pretty dumb honestly but it can't be helped.