@Nolonar
She has unlocked the eye of emo, so she can see what lead up to an emo situation. In this case the entire confession was important backstory so she saw it all.
Dang, I was hoping with all the build-up and development Komi-san had that it would've led up to something, but it looks like we're moving back to silent Komi. Ah well.
@Serenata There is also Agari (gourmet girl) on guitar, I think Onemine (sister) on the bass to the left of the scene, but you can see her only on one panel and from really far so I'm not sure. Najimi on drums and as someone already said Yamai (Yandere) on the keys.