Please allow the option to add customized feedback for individual responses in the Question interface. Right now the only option is to mark a question correct. If you could display feedback in the form of text, photo, audio, or video that would be awesome. Maybe the solution could be to display a particular layer based on the response for maximum customization. Right now, it is possible to achieve all of this with variables, but it is much more complicated to set up than it needs to be.
You could model the interface used for other elearning applications for delivering feedback (answer-based or general feedback).