So the reason that they spy on foreign companies is that they hope they can catch bribery going on (if they had credibly evidence without the espionage they wouldn't need the espionage in the first place, thus there must happen that they spy on innocents).

Once they find evidence of corruption they confront the government that is buying, not the one that could punish the company. Clearly the crime of corruption is not of importance to the CIA (why would it, they use it to recruit, and they aren't a police anyway).