The kbd48CNC MUST be connected to the PoKeys device with the cable originally provided. It should not be extended!
What are you referring to regarding that not all actions work? Mach3 or Mach4? In Mach3 you are free to remap signals on your own in the 'Mapping' section of the plugin settings. In Mach4, the keyboard uses the default set of actions and since not all are supported by Mach4, some actions may not work. However, you are free to use the 'Map to Mach4 signals' option and configure all buttons and LEDs on your own in Mach4 directly.