Quick reply is unless you have laid the ag pipe lower than the top of the foundations, and, it flows freely downhill/downstream to kerb or outlet, and, sealed the external wall down to the level of the ag drain,
then you have wasted your time.
The core flute is ok once you have done the above but only to protect the wall sealing from the rubble/stone
A pic or drawing of the home will certainly get you more info.