@unime I think it would be unusual for most elementary schoolers to be truly
adept at embroidery, at least. Capable, but not necessarily super skilled. However, we know from the manga that Takasugi finds joy in sewing and does it a lot (it seems to be her main hobby), and we also have seen several times that she was often left out of games as a kid and spent a lot time by herself. That would give her plenty of time to get better at embroidery than the average skill level for her age. Passion + time to practice = skill.