Well, I don't think that the Greek Orthodox would agree with such an equivalence.
It may be correct to use the term "the Catholic Church" to describe the first couple of centuries of The Church as it encompassed all the lands from Britain to Mesopotamia and Ethipoia (and beyond) -- and perhaps the term "the Church Catholic" might be an even better term, or simply "the Church" -- but not the "Roman Catholic Church".
At any rate, Calvin's usage of the term "The Church" generally assumes the Roman and Greek Churches together with some of the smaller churches as constituting "The Church". His localized frame of personal reference is to the French Catholic Church in particular, of course, but generally his larger frame of reference includes all orthodox Nicene Christians, not just the RCC.
Does that clarify Johnny's usage at all?
Best, OP