Ki is an abbreviation of Kiati(I know I am spelling it wrong
) which means airframe in Japanese I think those aircraft were on loan to the IJA also like some Ki-67s were loaned to the IJN
no, the spelling is off but you are right about the roots of the words - just a quick refresher for some of you if you are interested.
「キ」Ki - kitai - 機体 - airframe (note anything above the 200 designation was considered a jet or rocket powered craft)
「ハ」ha - hatsudou-ki - 発動機 - powersourse (for jets, 'ne' - 「ネ」 - 燃焼噴射推進器)
「ホ」ho - kikan-hou - 機関砲 - machine-cannon (as in mechanically repeating cannon), used for gunes over 20mm usually. Machine guns were called kikan-jyu (機関銃)
there are further designations for types of planes (gliders and such), for parts of the planes (popellers and such), and for spacific insturments (gyroscopes, altimiterrs and such).
Also, there are designations that come after the plane designation (like KI-84-1a - the '1a') that also have spacific meaning - but I will spare you all the language lesson.