Very interesting topic.
As far as I know, according Airbus policy, no overweight correction under non normal condition is required.
But if you have to divert because of a sudden decommpression or passenger illness these scenarios are not covered as non normal on QRH. So, just according to the papers the overweight landing correction should be applied.
BUT it is funny (against any airmanship) because if you have to divert to a short strip (i.e.ETOPS era), paperwise it might be better to denergize the yellow hyd system or even shutdown an engine (really radical) than correct the normal landing distance by the overweight factor. In the first case resulting landing distance (on paper) will be lower than the second.