That's a lot of words but you didn't answer the question. The CIA and FBI are not accountable to Americans. You may be a fan of, or even work for, these institutions. But they are unaccountable and authoritarian and opaque.
Accountability likely peaked with the Church Committee (disclosed MKULTRA, COINTELPRO, etc), some of the results of which are still classified today, almost 50 years later.
None of those programs were canceled, or the leaders prosecuted. All we imagine we know about them is what they published. Most people believe they tried to use ESP for spying, but all we really know is that they wanted people to believe so. Jon Ronson discovered recently that they still want people to believe it.
It was a PSY-OP against the American public. The runup to the Iraq invasion was another. There certainly have been others.
https://en.m.wikipedia.org/wiki/Church_Committee