"Set TOGA"
According to the FlightGlobal extract, the ECAM message displayed “ENG THR LEVERS NOT SET; SET TOGA”, an instruction to set the throttles to take-off/go-around” power. The copilot...... read the first part of this message aloud, but not the instruction to increase power. The captain responded that “the power is set”, adding that he had advanced the throttles to the flex position."
So it is really a bit hard to blame the Airbus system, setting TOGA from Flex is simply firewalling the levers.
However if they are left in FLEX without a flex power computation I don't know what it would go to.