Yes this could be great also. I was thinking four shortcuts but if it is possible to navigate events and angles separately it makes sense that you could have one button to mark on off the selected item. Then we need up and down (there is already) and left and right buttons. Though I still think that fastest way (little different thing also) could be four shortcuts to immediately play the the corresponding angle of the selected event to the output. So not to mark/tick the angle but instantly play it. This way it is possible to decide the order of the angles on the fly.

These all above shortcuts could exist together. So many ways and situations to do things :)