Partial or full threading are both fine. There was some debate on another topic about whether partial was better for the bearings, but machines are getting built with both kinds and are working just fine. I just examined my machine in terms threads length. I did not find any place where 15mm of threads wouldn’t work, and you might be able to go down as low as 12mm. The bolts in your link are galvanized. Personally I don’t recommend galvanized bolds for your machine. It has been my personal experience that the coatings can sometimes increase the diameter of bolts, and tolerances in the printed parts are tight.