Pilot monitoring has eyes inside the cockpit for the control check. PT says 'control check' I look at the GERMAN cross to see what the opposite sidestick is demanding, then I look at the flight control page to see and confirm that the correct flight controls have moved in the correct direction and by the correct amount.
What makes you think that the system which displays the GERMAN cross will show a different indication to the control deflection? If there is an error, it will affect both presentations in the same sense.