I haven't seen a claim that fake users played a large role in spreading propaganda or fake news. As far as I understand it the issue lies in what people were sharing and what Facebook identifies as trending news.
That's a pretty different issue from Twitters fake accounts.
I've seen stuff debunked by Snopes ECT so I link to Snopes to show my friend that what they shared was fake news, only to see him share the same link next week. He claimed he did not read the article but it agreed with his political views so it must be true.
I've seen fake Twitter tweets as well that have bad spelling and other stuff in them that it is obviously a fake tweet made by some website fake tweet generators out there. Then shared on Facebook as an uploaded image. If they don't link to the original tweet on Twitter consider it a fake tweet.
Your criterion for determining a fake tweet doesn't work if someone regularly tweets things and then deletes them. The combination of this behavior and abundant fake tweets allows people who like and who loathe a particular person on Twitter to build up opposing views of what is real.
I haven't seen a claim that fake users played a large role in spreading propaganda or fake news. As far as I understand it the issue lies in what people were sharing and what Facebook identifies as trending news.
That's a pretty different issue from Twitters fake accounts.