As far as I know, the only solution to make sfplay~ loop backwards is by using the preload message and creating a cue. Ok, this works fine.
But how about going to a specific point of the cue? Sending the seek message you can do this but only with the loaded file, not with the cues.
That is, if I load a file and create a cue (for example cue number 2) which is the abovementioned backwards cue, if then I use the seek message to go to a specific point of the file it works fine. But if I try to use it while playing the second cue, it would just jump to that point on the main file, not on the second cue which was being played, and continue playing.