It's an often-mocked cliche for the protagonist to be romantically-oblivious, but in this case I'm genuinely glad Uesugi is that way. It lets attraction to Eito be something they can just enjoy instead of being an immediate source of sexuality/gender/relationship angst.
Most of the guys in class are still total creeps; dunno if they think they can be more obnoxious to Kei-chan specifically or the other girls are just desensitized to this crap. Although the worst part is how plausible it is for them to get away with it, because they're technically insisting on a school function. They had dances like this in P.E. when I went to middle school (i.e. the US in the early 00s), and this chapter demonstrates why they kinda shouldn't have. With any luck, Noel will ask Kei-chan in the room during the trip.
Speaking of dancing, getting this much for just a rehearsal is curious. What could go different enough for the actual folk dance to be this big of a deal?
To expound on the editor's note, Uesugi-kun is consistently high on the "most read" list for Ciao+ all month round, when most series drop off with a day or two of a new chapter. It also has the most likes per chapter by a significant margin. A few weeks ago, the print magazine Ciao Deluxe ended, and its last issue included the first chapter of Uesugi-kun. We'll have to see volume 1 sales to know if this is more than a "big fish, small pond" thing, but either way it's done well enough to last for a while.