Had the same experience (trying to setup GNB on a controller), and overall I just feel like GNB has too many buttons that do practically the same thing; e.g. Bow Shock & Fated Circle, Danger Zone & Burst Strike, and an entire 2nd combo just for Continuation, really?

Could the cartridge spenders not simply have been oGCD Abilities (i.e. 'trigger pulls' between slashes) and the main combo replaced when in Continuation mode?