To give my two cents on the Falcom leak there are some things that make me suspicious:
-Someone already mentioned it but the leaker tells us about the thought processes of the parties involved. It's one of the most classic tells of a fake leak as leakers aren't usually privy to such "intimate" matters that would only be known by the key people involved, they just know the facts and that's it.
-The Crossbell games (Zero and Ao). The leaker says they would be announced "soon" for the PS4,
but they had actually already been announced at the beginning of 2020. Unless they are talking about a localization in which case the leak is simply not right about this one.
-Speaking of the "unpredictability" of the Crossbell games, this wasn't the only 4chan leak predicting them.
Case in point. If this particular monkey on a typewriter hadn't centered their post on a falcom partner showcase that obviously didn't come to pass, we might be talking about Estelle right now instead of Adol.
-Still on the subject of said Crossbell games, the leaker uses their recent fan translation titles instead of their actual official titles.
-The leaker cannot say who the character is (lol) but they doubt between Adol and Rean... main characters of two different series. It's not usually how Nintendo picks characters (by game/series, rather than company).
-A cold steel spirit event even though Rean is one of two candidates to playable character doesn't seem to make sense. Unless it's his spirit board. But if his spirit board is centered on his own series why would he also bring music from Ys? Our company rep, Terry, brings spirits from different SNK series.
-Speaking of music, just how is this leaker privy to the number of tracks? This goes beyond mere negotiations, this is Sakurai discusses content to be implemented with the devs territory.
tl;dr this leak seems far from foolproof to me, at least so far.