I never finished Revenant Wings (actually, I couldn't figure out how to finish Revenant Wings. As far as I can tell, the game is basically unplayable after a certain point), so I can't really comment, but what I saw of that game also fit in reasonably well with the whole canon of Ivalice. It occured between XII and Tactics, and doesn't exactly ruin any of what we had before.

And FFTA2, again, fits in with what we had previously. Sure, several main characters take a vacation to Jylland, but that is not exactly lore-breaking. The only real problem (aside from the butchery of the main story, and, seriously, why did they do that when the rest of the game is as awesome as it is?) is that it attempts to directly tie FFTA to the rest of Ivalice, which can't be done.

I mean, maybe I'm missing something, but how did Revenant Wings or FFTA2, on their own, fail to fit into the Ivalice lore?