I do like these puzzles that let folks flex on esoteric knowledge.
As it turned out, I figured out what to do pretty quickly for hard mode, but even then was too afraid to actually try lest my thought process be incorrect. The blend of elements here also makes esoteric knowledge a burden just as much as it helps! Gems have weird rules with pushing/crushing. Duplicators mean you can play with the stat order of what's on screen, and crushing things can have weird effects if the element crushed is earlier in the stat list which sent me on a wild goose chase thinking there might be some way to use all these to destroy the key somehow.
Honestly I was even wondering if the colors of the sliders was in some way relevant!
Gave an extra star in sounds because you're not the one to blame for duplicator sound effects.