You did a great job as it's not readily visible. I had to do a somewhat similar repair on the very first quilt that I was commissioned to make - of course, as some of the fabrics started to come apart. Since it was a Roman Stripe quilt, and there were just a few problems, not sure how that happened unless I got some older fabric. I hand appliqued the black triangle, then machine quilted the diagonal lines used in the rest of the quilt. He was happy with the quilt, however, I as embarrassed that it happened, especially since it was my first major commissioned quilt.

Good repair.