The 50 was a later addition to the 7 system, with the 210 later still.
The 210 does not appear in the hard-copy Mamiya 7II brochure I have that has a MAC imprint on the back along with document code numbers 3ED-2211/E991110. It does appear in a later electronic version I have of the same brochure, also with MAC imprint and code numbers 5ED-2211/E040102. I also have hard copy of a one-page MAC sales sheet for the 210, dated February 2000.
I used to have the Japanese-language home-market instruction manual for either the 6 or 6MF - I forget which - that came with a body I purchased second-hand in Tokyo in 1992-93. Alas, both camera and manual are long gone, and I don't remember this detail from it.
I think I have some Japanese-language brochures for the system buried somewhere as well, but it might take me a little while to dig them up.