If you’re looking for a way to do this within Studio, you can use a Tempo Marker & Marker with a Transition Region & a Transition Marker. Place a Tempo Marker on your Event to match your music, with a Marker at the beginning. Place a Transition Region 50 seconds after your music has finished that lasts 30 seconds, setting the destination to your Marker and Quantization to anything you wish. Turn on the Probability condition and set it to around 10%. This will give each transfer point a 10% chance of looping back to the beginning. Place a Transition Marker at the very end of the Transition Region to catch the cursor should it reach the 80 second mark without transitioning.
Please see the below screenshot for an example.
An alternate way is you can place your music into a Scatter Sound and set the Min/Max Scatter Distance to 0, Polyphony to 1, and the Interval Between Sounds to however long your music length is plus 50~80 seconds. In order to get this method to work right, the Scatter Sound needs to be placed on a track in a Game Parameter tab.
However, it will probably be better to use scripting in whichever game engine you’re using to add a random amount of wait time before looping again.