One of the rules of harem stories is that all the girls have to enter the race before the elimination process begins, one by one.
That's why
I don't think Moe will confess at this festival. My reasons are:
1) The MC isn't even aware of, let alone suspicious of, Moe's feelings yet. Springing a confession on him out of nowhere right now would give him a shocked Pikachu face, followed by a rejection later on.
2) Actually, this one-on-one time with him is a good turning point for Moe to
find the resolve to seriously pursue him. Right now, she's still a Kusunoki worshipper living in her shadow. Moe hasn't developed much agency of her own yet.
3) Hebikawa hasn't even entered the race yet.
4) The author moved Kusunoki out of Keisuke's class and put three of them in the same class. This might be a way to keep any one girl from advancing too far ahead of the others. Moe confessing right now is definitely too premature.
Anyhow, that's just my opinion.