I mean, besides getting WFT correct, which was undoubtably the hardest read until PP, and Villager, who was the first example of Sakurai changing his mind, the only elements the leak got "wrong" were accounted for in other statements, or in the data.
Not only that, but all the things that were "wrong", could be traced back to the same early period of development. Before Sakurai settled on Greninja, the spot was simply reserved for an "X/Y character", as per the leak. Before Sakurai switched to Robin, Chrom was intended, as per the leak. And at some point in development, as per the datamine afterwards, there was a Rhythm Heaven character planned.
Everything lines up to an earlier period in development. Literally every character in the leak was in the game, or intended for the game at one point, there are no loose ends. It was obviously real, just not reflective of the final product.
Also, how obscure can the leak be if we're still talking about it seven years later?
No offence, but idk why you're trying to speak empirically about this stuff when you're obviously less informed about it than the people you're discussing it with.