Good day to all Pilots,sit down and have a tea. I'm here to answer all your questions regarding the Kempeitais business. But since I am not very often in this system, I cannot promise to answer your questions the same day.
Regarding the Shogun title thing, I suppose he could use it as an alias, while his title is something more in line with the lore.
General Katsumoto Kumo, "the Kenpei Shogun".
Using it as a self proclaimed title would amount to that, as the significance of the name on the lore prevents the recognition of more than one. It's a Supreme Commander rank.
Other than that, I believe the kenpeitai would be suitable for a translated army hierarchy, or a secret agency ranking.