I would think there is a way to tell the system some basic rules, so its not completely unsupervised.
Like: Here is a list of all stitches (so it doesn't create its own), and the number of stitches must be correct for dimensions, or something like that. Then you validate all the input data against that, and move on from there.
Its a bit more complicated than that, since the only constraints is the yarn and physics. And there's infinite possibilities of stitching things together in intricate manners.
Then deciding whether something is nice/wanted, is in the eye of the beholder :)
Like: Here is a list of all stitches (so it doesn't create its own), and the number of stitches must be correct for dimensions, or something like that. Then you validate all the input data against that, and move on from there.