In something I'm not entirely sure if it's an overlook or a design choice, as of the recipe to extract fibre from dried retted plants lack a [noquality] tag on the ingredient, which is produced with said tag.
Tuukka has seen some fine fibers. I checked his stockpile and im showing fine from spruce bast. Which isn't the right plants. I think he had fine nettle/hemp fibers that he used in his clothes. It will be a while before I have a fresh stock of retted hemp/nettles to check again.
Weaving in real life was something people, typically women, specialized in so I think there should be skill ratings.