Well, to be fair, being trapped in it doesnt necessarily mean knowing about it. Barry didn't study it or anything, so there's no reason he should know. Being in the Speed Force is basically just an eternally blissful morning run, so I don't consider being trapped in it something that would give knowledge of it or anything. So with that in mind, Wally would know more than Barry.
When you brought up both Flashes bringing Bart back... I realised, who would he work with? Yeah, he'd be independent, but he has to work with either Barry or Wally. But if Wally is training NuWally like interviews imply, that just leavew Barry (was that ever a good thing? Again, didn't read much of the 2010 run)... or MAX!!!
Honestly, I'd prefer Wally be the one to find Bart, since Bart started out as Wally's sidekick. And to balance things out, you can have Barry find the original JAY, as a call back to The Flash of Two Worlds... maybe both in the same story?! And all four reunite with NuWally and there you go, the Flash family begins with one awesome two-page spread of the Flashes united?! Let me dream