There are not three hydraulic systems on an A350. There are two traditional hydraulic systems and the "third" is self contained in the actuators and electrically powered. Even with loss of the two traditional hydraulic systems you can still fly the plane.

I am guessing by not being configured properly in a go-around you mean the landing gear can't be retracted - however a go-around can be flown with gear down, and in fact in the case of a windshear usually is until at least the windshear warning clears.