To the creator: What about all the other plugins and macros that already use "s" ? I'd love to try this out, but remapping basic keys has always led to some other function or mapping or macro suddenly failing.

Why can you not rework the "f" key itself to take 2 keys if pressed in quick succession? "f" waits a millisecond to see if another key is pressed, if not it behaves identically to the default "f", else it uses 2 or even 3.