But were the leaks put out by Wikileaks about the DNC false in any way, or just inconvenient? Can there be any doubt that the DNC very much preferred Clinton to Sanders, and did what it could to get the primary results that helped ensure Clinton was the candidate?

So far as I have read, the distortions and spinning, and the fabrications were very much home produced. The Russians may have supplied some of the tinder, but it was Americans who piled it high round Clinton and set it ablaze. I've seen no indications that material eminating from allegedly Russian hackers was forged

Perhaps the biggest single and most crucial bit of fake news was the con pulled by the FBI ten days before the election, when they issued a scare story about "freshly available" Clinton emails, with an implication that they wre horrendously incriminating - when in fact they do not appear to have been either freshly available nor incriminating. And neither the Russians nor Wikileaks (hardly the same thing) had anything whatsoever to do with that - and arguably it put Trump in the White House.