I had a blast playing this. I really love difficult or tricky platforming and this was very cool. The reverse platforms are managable, I ended up skipping every lag platform because those are impossible xD
Something else, in Unity when using pixel art make sure to turn compression off as that makes your pixel art look blurry. You can do this by clicking on the asset and then changing it in the inspector. (You should also ensure that your pixel per unit is the same for every pixel art asset, which should be true by default)
Since you asked the difficulty curve is fine I think, the only thing I'd maybe needs changing is making sure you can beat the game in one run without respawning. At least I wasn't able to beat it without repsawning