Actually, EASA only cares about time under Instrument flight rules, not about IMC at all (except during initial training). So yes, off block to on block.
AMC1 FCL.050 (a) (5) Operational conditions, namely if the operation takes place at night, or is conducted under instrument flight rules.
AMC1 FCL.050 (i) (7) column 9: enter flight time undertaken at night or under instrument flight rules if applicable.
As long as the whole flight is under instrument flight rules, which is the normal way for A320 operations outside private ops, the whole flight time (which is the same as block time under part FCL) can be logged in column 9. Additionally one can log IMC time in the remarks column at ones leisure, except during training for a license or rating, then one has to log instrument time in the remarks column.