Blender does not recognize the BTT Shift modifier.
Under the Trackpad Menu, I have the 4 Finger Swipe Right gesture assigned to the Custom Keyboard Shortcut [Shift A] which should bring up a menu to add an object. Instead, it toggles the Select/Deselect action which is what happens when you enter [A] without the shift modifier. Can this be corrected?
Apple Magic Trackpad and MBP trackpad
BTT 2.625 (932)
Blender 2.79b (www.blender.org)