The Bulgarian bag rotational swing aka shovelling swing is the transverse plane version of the traditional linear swing. The movement is quite similar but there is some thoracic rotation toward the bottom of the swing plus, you will need to keep your feet close together at hip width apart so the bag can swing outside the legs.
Also… remember to wait for the Bulgarian bag to go passed the legs before you initiate the hip hinge, then, use a powerful hip snap to power the bag forwards and upwards.