Airbus does not forbid Last Minute Change in fuel. Although most operators have last minute change limits. This is a few hundrets of kg of fuel, depending on the operator.
Airbus A330 has automatic fuel trimming. It's pretty sophisticated, basically after top of climb, fuel is being pumped to the back to achieve a tail heavy configuration for optimised fuel burn (horizontal stabilizer producing lift). Before landing, fuel is being pumped forward, to be nose heavy, more stable for landing.
There were no ECAM warnings for the fuel system on AF447. All warnings were live transmitted to AF maintenance and are fully known and understood.
Dani