Just to make an important point:
The FCU altitude readout is the INPUT to the computer. The PFD altitude readouts are what the computer has received. The three should of course always be the same, but if there was a fault somewhere, they might not be.
Therefore, as has been said the only place for Airbus pilots to confirm the selected level/altitude is on their PFDs.
Our SOP's are for PF to make all selections unless they are hand flying, in which case PNF makes selections on request for them. If a new Alt/FL is selected, whoever made the selection calls what they see on their PFD, including the colour of the digits*. The other pilot looks at their own PFD and also calls what they see. The two should of course be the same, but this is an extremely important check to make, because it can catch incorrect selections, computer faults and therefore Alt busts.
*Because on Airbus, constrained intermediate altitudes are coloured magenta, unconstrained ones are Cyan (though we say "blue").