Alternatively, connecting the Dualsence to the U5 and the Dualshock4 to port 3 of the Xim Matrix will also solve the touchpad problem. The reason the touchpad cannot be assigned keys is because the Matrix recognizes the U5 as an XBOX controller. Therefore, if you connect a Dualshock4 or Dualsence to the Matrix port for authentication, the touchpad can be assigned keys.