In the burgeoning genera of precision platforming with imprecise controls the actions either need to be forgiving to allow for the player to adapt to the new control scheme on the fly or deterministic to allow for the player to intuit the changes as they happen.
The timer for the levels seems to be a bit too strict to give a player time to adapt to the changes, especially if they're using a trackpad.
Additionally the mouse over detection for the remaining buttons seems a bit hit and miss and would cause me to lose a lot more time replacing the action I didn't intend to remove.
If you're going to continue with this I'd recommend either going in the direction of giving more precise control to the player and doing away with the mouse component (as that requires taking hands off half of the controls) in favor of being able to hold some button to rebind what buttons should have or something or being more forgiving with the stages (by not making enemies 1-Hit-KO and instead cause physics effects like launching the player in the direction they came so as not to punish a small mistake halfway through a stage with the same punishment that a major mistake would cost).