Hello again, this has now been added! Let me know if you have any issues or feedback otherwise.
I decided not to add a dedicated looping region setting for now. You can still set a preview section and loop that, if applicable.
I added a loop toggle button to the player, which allows you to loop the playlist or a single track repeatedly. I didn’t add the shift-click play to loop, I figure the loop button toggle is more intuitive. I may change my mind later