You should use Hepburn, it is the best method of phonetizing Japanese. Period.
Also, the hilt is called Tsuka, and the blade part from the Habaki (collar) all the way to Kissaki is usually referred to as Nagasa. Your terms might or might not be correct, I’m not an expert in Japanese, but surely they won’t get you anywhere in the blade community.
Congrats for the pair! It looks nice for production pieces. What brand are they? Ronin Elite?