> I can’t imagine them making a series of them in such a way that it bolsters or proves the author’s claim AND goes completely undetected by everyone involved.

The small minority of cases that do fit this pattern get selected to be on the front page of HN. So we aren't drawing from a random sample of mistakes. All the selection effects work against the more common categories of mistakes showing up on the HN front page, such as author disinterest, reader disinterest, to rejection by the journal, to a lack of publicity if the null result is published. The more reliable tell that it's a fraud is that the authors didn't respond when the errors were discovered.