31? Where'd you get that figure? The quantity is in the single digits, only about 5 by my count, and not very large screens either. If you want to stretch it to 6, there is one area with some very small frog shadow silhouettes behind physical leaves over the boats (the leaves also move with the silhouettes).
Around 95% of the ride is comprised of very detailed and quality physical sets. The ride unquestionably needed more animatronics (and more length, my primary complaint), but it is NOT wall-to-wall video screens like Toy Story Mania. Navi River has a far higher ratio of physical sets to screens than even Gringotts or Kong. I'm not defending screens, even if they are well executed in Navi River (as far as screens go, still not my thing and i'm an AA person all the way). But they are honestly a rather insignificant chunk of the ride.
Flight of Passage didn't really impress me. I don't technically dislike simulators, but I don't consider them valid substitutes for an actual ride (would prefer the third attraction they cut). It's a very good and enjoyable simulator, and I might ride if I can snag a fastpass. But not the amazing earth shattering experience some were claiming. I wasn't hyped and expected a good simulator, that expectation was met pretty much exactly. Navi River was far more special to me IMO. It's no Splash Mountain or Spaceship Earth and absolutely has flaws, but within its own scope it did remind me of that old classic Disney "magic" (quality) I find so rare in newer attractions.