Why not try the cleaning on the ones behind the fridge? Get and try the Novus, Lexan/plexiglass cleaner system.

Would Jubilee Kitchen Wax work?

They lose their shine from oxidation and from abrasion from scrubbing. Time is what causes the first, and overzealous cleaning the second. There comes a point when time has marched on, and you cannot recapture their youth. The risk of polishing them is that you are removing the surface. The positives of polishing them is that you are removing the surface, and the oxidation. If they are already too abraded though, you may be removing more than you want, so you may have to accept some of their existing condition cannot be fully reversed.

^^^^, hence I mentioned trying it on the plastic tile behind the fridge.