Transit passengers are only permitted to use the Pier lounge or lounges such plaza premium, Chase lounge (just opened). For passengers originating their trip from HKG, they can access other CX lounges located near the departure hall. There is a check-point around gate 12 or so, once the passenger passes this point, they can not return to the departure hall area. Obviously transit passengers are not allowed to pass this check-point either. There seems to be more shops and restaurants near departure hall area (from pictures I see online). Flights to China are departing from that area as well.