Why Leon doesn't know Barry? Barry's works for STARS, Leon worked in RPD, there are records of him in the database, so unlikely someone from RPD & CIA doesn't know him.
Barry was long gone from the RPD when Leon joined. Actually, Leon never joined at all because he was quite busy fighting off zombies on what was
supposed to be his first day. But all I was trying to say is that the game doesn't give us any indication that Barry and Leon know each other, and so far you haven't provided any reasonable argument for your theory that they do, besides Leon being a special agent, which apparently makes him omniscient in your view.
If Ada knows everyone, why wouldn't the CIA & BSAA?
Hell if I know, ask Capcom. But Ada is
shown on screen to know almost everyone, just like Chris is
shown to have pretty much no idea who she is when he first meets her doppelganger in Edonia. Perhaps
someone of the BSAA knows about Ada, but clearly not Chris at this point, so your argument that everyone knows everyone just because they're coexisting in the same game universe is proven wrong by the game itself.
If Claire knows Leon and has met him in Degenerations, she would have learned about everybody except Jake since Leon knows everyone involved.
You're right, I totally forgot about that scene in the middle of the movie where the two of them sat down by the fire, having tea together and gossiping about every other person they have ever seen, met or heard of in the course of their years apart. My bad... I guess.
Wesker probably knows Jake before he died. I mean the guy knows everything. But not his son?
The fact that Wesker even
has a son comes as a huge surprise to almost everyone. There, another thing the BSAA (or at least Chris) didn't know until they were told by Leon, who learned it from the data Sherry gave him, and Ada, who knew it too, learned it on the submarine. I don't think we are ever told how this information came to be known in the first place, and we are certainly never told what, if anything, Wesker knew. But considering his character, it seems likely that if he
had known, he would have either killed Jake to make sure there's no one else like him, or included him in his plans, neither of which happened.
I say Jill, Barry & Sherry are probably the most ill informed ones but because they are close to Chris, they know what Chris knows.
Sherry is nowhere close to Chris, but if you like to think that Chris shares everything with all of his friends on a regular basis, even the most unimportant information, there's no way to disprove it, I'll give you that. So Jill might as well know about Steve and the crush Claire had on him... who knows. But I'd like to remind you that much of the conflict in RE6's plot stems from the characters' poor communication skills.