I seem to have made a ghost chord. Pressing it doesn't trigger it, and it doesn't appear in the device manager, but I believe it exists because if I enter its output into the impulse chording menu, the menu suggests its corresponding input.
The chord I tried to make would map KM_2_L + DUP + l to "four", and I created it through the impulse chording menu.
The impulse chording menu should probably prevent the creation of a chord you can't trigger. Also, the device manager should let me delete it; probably both of "the device manager should be able to display this chord to me" and "the device manager should be able to notice chords it can't display and give a way to blanket delete them" should be true, but either one would be good enough.