The "evidence" against Cardinal Pell at trial was scant and not credible. One small point -- I'm not sure the media convicted him from the start, as you suggest, if for no other reason than in Australia it is illegal to report on criminal trials of this sort. There was not a whole lot of coverage, and the little I read during the trial seemed to favor Pell's defense that there was no evidence to support the charges..
Now, there is evidence that Becciu transferred a significant amount of money to Australia before the trial. There is speculation that it was used to pay off the primary accuser, to suborn perjury, although I have not seen any reports that this has been proved. Becciu filed a libel suit against the Italian newspaper that reported it. What is clear, however, is that Francis forced Becciu to resign as a cardinal, which shows that Francis knows something significant.