yeah that a pretty off rumor.
Fett shows up in one book and fight together with Han to get away from the Vong.
Yeah the Jedi are pretty pathetic to the Vong. They can't feel/see/touch them in the force, so they are just voids. And the Jedi can't anticipate their moves.
the whole Series started badly had a good middle and ended badly. I'm suggest reading them ONLY to be able to appreciate the "Enemy Lines" books (2) they ROCKED!
But yeah, my main point is that the jedi are all whining about not being able to see them. Ok so what, you can use your eye, pick up that bolder and drop it on them.