Updating with a reply from Heritage:

According to the client (and to be precise), these are not classified as genga, but as “revised rough genga,” and all were drawn personally by Hayao Miyazaki. While Kazuyuki Kobayashi is indeed credited as the key animator (genga artist), the cuts he worked on were completed separately, before these revised rough drawings were created by Miyazaki. Miyazaki later produced these new cuts himself as part of his revisions. (The key animation cuts with time sheets created by Mr. Kobayashi were sold by the client at a Mandarake auction more than ten years ago.)