@EnduranceProtocol I think it does at least help show that she had friends outside of the others we know, which helps build up the fact that like normal people do you have friends in your classes and friends in your clubs and such, but unlike those friends these ones she may struggle to see again. It's more of a farewell than a see you later in that sense.
And yeah, trying to do this well but not slow the pace is tricky and as a reader we wouldn't want to have multiple farewells going on if the reactions we see are the same in most cases, i.e. Kanade getting sad. The impact would begin to be lost as they dragged on because the message would have been brought across in the first part.
Plus to some degree, I think they have been doing more spaced out farewells. In a way, she said farewell to her teacher through thanking her for all her help a few chapters back along with her final recital performances, and that can sort of apply with her other friends too.
If we're talking the featureless girl on page 27, I'd agree that's Yuki. I was mainly referring to the photo on page 34, where Yuki there is more defined (she has eyes) but the friends in the left of the picture have little features beyond enough to give an impression of them.