That’s a beautiful quilt and it makes me sad that it wasn’t done properly! I have fixed extra long FMQ spots on my own quilting by hand stitching to mimic the machine quilting. Do you have any matching thread like the quilting? If so, take out a few stitches in the many....many ...boo boo spots, hand tie the ends and bury the thread ends in the sandwich. Hand stitch in a few stitches to complete the design, tie off and bury the ends. Quite a job but what else can you do?