I want to give my point of view of the sal leak, first, let's remember that sal himself isn't the leaker, he has a spurce that sends him emails when he feels like it, now I think I discovered 2 things about his source
1. His source doesn't seem to be working with sakurai's team: I think his source isn't working on the game, Why? Let's remember that sal got wrong the reveal dates of little mac, pacman and the mii fighter, if this guy is working with sakurai's team then he should have known which characters were going to be at the e3 and which not, also the guy couldn't say which pkmn from x and y was chosen and who is the winner between ness and lucas, this also makes me think other things
2. Sal Source contact could have stopped getting information before the roster was finished: I think this because he was unable to say which pkmn from x and y was picked and if lucas stays or not, this could mean that the source for some reason wasn't working anymore with sakurai and his team, now let's think about the development, these are pure assumptions and I could be wrong, I think the first thing they do for a smash game is which character returns and which not, then they pick the newcomers, now this depends on how early greninja was picked, I think he was picked very early but that's just me, now this could explain why didn't the source leak Rosalina, it is because Rosalina was picked after greninja and therefore, the source didn't know about her, this could mean that the source doesn't know of the full roster, in other words, the contact of sal source stopped getting information before the roster was finished