Slogged through maybe four dozen testimonies and Copland is the most sympathetic. Wouldn't even call him a useful idiot. He wanted to perform and communist front groups around the world invited him. Maybe he was just a good actor but his comments seem sincere. None of the others do.
Scroll down a ways in volume two to read his testimony.
Don't miss Auerbach and Mandel. They were true believers. Mandel thought the Doctor's Plot was imperialist propaganda.
Interesting account near the bottom about the "Austrian Incident". Frank Coe, working at the International Monetary Fund, overvalued the Austrian currency in 1949 to destablize the country and favor Russian occupation forces.
Where did you hear about all of this stuff (you seem to know a lot of these stories prior to even reading the docs?)
This sounds like an interesting subject for a paper.