DutchOne, you are right, fuel is used from inner during takeoff, central (if any) are emptied in flight, the outer fuel is spilled onto inner.
Hot fuel returning from the engine is sent to the outer and excess spilled to the inner (that is the reason while it is normally warmer than the inner)
I had exactly the same tought, that 54º is a limitation to USE the fuel, but the vague FCOM wording made me doubt
Thanks for your answer