First of All, I would recommend completely reversing the process. Assign functions to keys, and not the other way around.
X-Plane has this done very neatly, because it will show you a model of your controller, you can click on the individual buttons, and assign functions to them.
Second thing is, I would make the functions much more clearly defined. For example, what is the difference between Throttle Axis and Throttle Axis set?
Current implementation is catastrophic, and I can’t imagine a newcomer (for which this Sim is intended to!!!) to be able to orient in such confusing environment.