I'm not sure I follow. I have a specific event for which I would like ST to randomly select one of several audio files. Each time that one event is triggered you would hear only one of the files from the Sonos, so you wouldn't keep hearing the same audio clip everyday.
This is a novelty use case for me - when the cave is fired up for movies or gaming a short sample is played to set the mood, and I'm wanting to keep it from being repetitive. I'm not sure your recommendation addresses this - or I missed something.