Call me crazy, but I think there's value in finishing what you set out to do, no matter how much interest you may lose near the end. I agree that she's definitely beyond the point of, "I'll show them, I'll show them all!", but I think she would at least return to settle issues, apologize for the earlier incident, and close out her academic transcript. I can believe that she would decline to attend the graduation ceremony for fear of literally outshining everyone else in her class, but honestly I'd like to see Poe make an Errant Tale surrounding Meji's graduation. I think it would be doable artistically, and it would tie up that loose thread.
Errant Story is, fundamentally, a bildungsroman for Meji. Most stories in that genre also include guides, which we have, but a true mentor is conspicuously absent. I think it is quite obvious that Meji wouldn't even have been in this story without the challenge Sashi Mu issued to her and her class, and she certainly wouldn't have lasted through the twist and turns of the plot without the education and training she already recieved from that fine institution. No ship can sail the seas without having first been built on land, and I think Sashi Mu deserves some credit for having helped shape Meji from a child into a fine young woman.
Furthermore, I think it would say a lot about how Meji has matured internally if she were invited as an honorary speaker at graduation, and she gave an address that was not at all bitter or concieted, but rather was gracious and deferential to the faculty, staff, and students of Sashi Mu, kind of like a famous person coming back to give the a speech at their old alma mater. She could say that each and every one of her peers has the potential within them to exceed her own acheivements some day with commitment, dedication, and a few good friends.
In the background, Poe could also use the names and/or faces of his favorite teachers, professors, mentors, and guides from his own life, who all helped to bring up an artist with the talent and vision to create such a magical world.