What a fun party! Rina with the outfit, unicycle, and juggling was surely the best one! She deserves that shopping ticket.
Chihiro became depressed from multiple failures. You'd think because they were minor, it wouldn't make sense, but they compounded! Of course it would be depressing. It makes sense she got it in one try the next time, the frustration had lessened at that point. I dunno if Rui cheering her on helped though, if anything I'd just get more frustrated because I'm not accomplishing my goal.
I'm still not sure what Fukuyama was doing...