NigelOnDraft
As you have said the procedure to simply open cross feed was changed because in real life it may not balance the fuel due to pressure difference in fuel pumps. So they changed it to "imbalance monitor" and if you see the fuel imbalance procedure in the FCOM at bottom it says:
Note: There is no requirement to correct an imbalance, until the ECAM fuel advisory is displayed.
So you do not have to do any thing at EFATO. When the advisory appears apply the procedure. That is how it is taught now. Incidentally airbus can be landed with one tank empty and the other full.