I can’t speak to any allegations about inappropriate behavior, but comments from random anonymous crew-members about the quality of a movie from their experiences of the shoot is absurd. The crew on Star Wars were convinced it was gonna be a terrible movie. The production problems on Apocalypse Now are legendary. Same with Titanic. None of this babble has anything to do with whether a movie will be “good” or not (putting aside what “good” even means — obviously some movies are divisive).
Quotes about Coppola being “inefficient” by choosing older production techniques are particularly ridiculous. It’s his money, why should anyone care how he’s spending it?