That was a fun read.
One thing I'd like to note about Kanade... I won't argue against her being somewhat privileged and lucky, but more than that, she makes creating and maintaining those bounds fun. Her relationships with her parents, friends, rivals, teachers and neighbours are not one-way streets. She's very engaged and mindful of them, and, if anything, naturally the most forward about them as well.
I'll extend what you said about Shouko being Shouko to everyone being their own person, and it's genuinely heartwarming to see Kanade kind of fumbling at the center of this wonderful cast she influences and is influenced by. Everyone stands to gain something in return, one way or another. And that's what I like the most about La Magnifique Grande Scène, and why, as a result, I love Kanade so much.
Also, while I still believe the series to be rather niche, I essentially knew nothing about ballet going into it. Like you noted, many of its facets are explored alongside Kanade, and pretty naturally I think, which was very compelling to me. I put in a significant amount of time just soaking myself in ballet for the purpose of sharing the experience... and, well, I guess I developed an admiration for the art as a result. So I'd recommend it to people who are into coming of ages as well.