New run with updated puzzle solution: 3,4,2 - must be in one move.

3 and 4 must be hit close together (in time), while 2 and 3 must be hit far apart. The order of 3,4,2 ensures this.

This new solution comes from the fact that pressing multiple buttons at the same time cancels certain platform switches, while the old solution (3,4,2,1) relied on all buttons being pressed independently.