It seems to me that the author simply doesn't know how to progress the story with some proper and serious drama, and is instead still trying to make it work through the slow burn slice-of-life elements. There was so much buildup to the Haniel cosplay, and i was so sure we'd get at least some serious progress on their relationship and plot. And I feel that hasn't quite happened. If anything, there seems to be no proper post-incident handling or cleanup after their cosplay blew up, so it sorta feels like a damp squib honestly.
I'd have expected this cosplay event to be the place where they saw and realised the professional world of cosplay, as compared to their casual cosplaying until now. Don't see that happening here. I mean, you could say they are still processing it, but moving right on the story timeline makes little sense while their processing is still ongoing