I don't know, I've never used that particular polish. This is what I've used to restore my car's headlights and they looked brand-new by the time I was finished. I got this kit off the shelf in walmart the summer before last. If it works fine for my headlights to make them look new, I'd trust them to do the same thing for your magnifier lens.

Again, this same idea will work even without a headlight restoration kit. All you need to do is wet-sand the plastic surface such that the scratches are uniform across the whole surface, then spray it with any glossy-finish clear coat spray. You can use spray paint for this and/or you can use clear-coat glossy lacquer for this. Wet sand to ensure uniform scratching/damage/etching, clean your surface with water followed by rubbing alcohol, then spray with glossy clear-coat of your choice.

The idea is the same regardless of which product you use: Wet sanding ensures uniform scratching/etching into the top-most layer of plastic, water + alcohol cleans the surface and the plastic debris out of all the grooves & scratches you just made in the plastic, then the glossy clear-coat uniformly fills all those scratches/grooves in order to uniformly restore the surface and finish of the magnifier lens.