I have just had a chat with a French accountant. A French AV in itself doesn’t have to be declared and will not show on your tax return, nor will the social charges you may have paid on interest in fonds en euro. Can you copy what Strictly fiscal actually said?
The only time this is not the case if if you make a withdrawal.
If you wish to reclaim the element of social charges which should be exempted because you have an S1 the you have to deal directly with the AV company.
I don’t know who provides the AV for Credit Agricole, but this should be somewhere on your contract.