The Airbus FBW system will maintain the attitude that you set with the side-stick - the pitch angle and bank angle - but it cannot do that in all turbulence situations, (and there are maximum pitch and bank angle limits that it works within).
In moderate to high turbulence, you will have to correct the attitude to maintain the path you want.
In extreme conditions and deviations you might have to hold full side-stick deflection for a moment to correct the aircraft. But remember, the way with Airbus FBW is to make a correction, then return the side-stick to neutral, correct, neutral, correct, neutral, etc.
In high turbulence, just try to keep the aircraft in approximately the required attitude, don't constantly try to keep the FD centred, just try to correct large deviations. If the turbulence is too severe, you will have to discontinue the approach.