Unless the aircraft was already being flown in direct law there's no reason the FBW shouldn't have coped with any rapid increase in thrust. In normal operation it's quite feasible to apply TOGA thrust rapidly and have the aircraft continue down the ILS path unperturbed. Were the aircraft deliberately placed in direct law then the actions taken would most probably have been verbalised and recorded on the CVR, along with the associated ECAM warning chimes. Even if the aircraft ended up in the unusual attitude variation of normal law the crew should still have had full control authority to move the surfaces, even if they had insufficient airspeed to execute a manouevre. The comparisons with the well documented A300/A310 stall events don't tell us anything about this mystifying incident.