Did operation cardinal ever happen

Answer 1

"Operation Cardinal" happened. The details of an OSS operation in Mukden, Manchuria, shortly after the surrender of Japan is detailed in an article by Peter Clemens entitled, "Operation Cardinal: The OSS in Manchuria, August 1945."

It was published in a journal called Intelligence and National Security (Vol. 13, No. , Winter 1998)

Hal Leith, the Russian/Chinese linguist on the mission, is alive and well.

I think the questioner is confusing Operation Cardinal with Operation Downfall which was planned for (I believe) November 1945. After the two atomic bombs were dropped on Hiroshima and Nagasaki, and the surrender of Japan less than a week later, Operation Downfall became unnecessary.