I remember that when I was a child there was one time that we had an older girl giving a model lesson to my class in-front of her teachers, my teacher and my class. I had made fun of her lesson(while she was still teaching) in-front of everyone, and I’m sure that it embarrassed her and hurt her feelings(then I was sent out of class by my teacher). Am I required to track down who she was and ask forgiveness?
You don’t have to, but “lotzais yiday shomayim” it would be the correct thing to do. This is similar to when a child steals something, even though halachically they are not obligated to pay the money back, but “lotzais yiday shomayim” that they should preferably pay it back as an adult.
R’ Y. Cahen shlit”a