@hotel you assumed correctly on what she was literally saying. Minami and Heike pointed that out in our discord a few hours after we uploaded but I was already off to dreamland by then and only got to correct it now. (One of the reasons why I dun like doing rush work.
Getting this chapter done within 3 days just after the raw got released. But that's the beauty of mangadex, you can fix-up mistakes with the edit button.
)
I think this chapter is a sort of revelation for Juju to see the amazing experience one can have when cosplaying with others. It's quite cute, she's thinking in her mind that Kitagawa is supposed to be a cosplayer she hates the most but realizes that it's not really true and that cosplaying is more fun when your passion and joy is shared with other fellow cosplayers. Basically, she was still trying to be tsun but ended up going dere-dere (I mean, who can stay mad at the lovable cinnamon gyaru roll that is Marin~? XD)