Quoting infrequentflyer789:
Also in the report they have said that the leakage was through the spar valves, which means (if I understand the fuel system correctly) that the fuel was from the main wing tanks, not the CWT.
Fuel leakage through the open spar valves, with the boost pumps switched off due to the fire drill, means there must have been a considerable amount fuel in the wing tanks. With the aircraft coming to rest wings level (which can easily be verified from published pictures), wing lower surface at the location of the spar valves has a considerable amount of dihedral downward to the rib separating wing tanks from CWT.
The spar valves are located somewhere outboard of the main landing gear and just inboard of the engine pylons and certainly not at the lowest point in the wing tanks because of spar valve location further away from inboard rib, separating wing tank from CWT, and dihedral sloping upward toward the pylon.
From the last picture taken of the aircraft while still airborne (taken from the left looking up toward the aircraft), one can clearly see the lower wing surfaces. The location of the rib separating the center tank from the right wing tank is clearly visible. The wing lower surface of the right wing tank has a frost layer beween that rib and engine pylon, meaning there is fuel in that tank, at least all the way up to the engine pylon. However, inboard of the rib toward the fuselage, the lower surface of the CWT has no frost which means no fuel is in contact with the lower wing surface in the CWT, hence the CWT is virtually empty.
Frost is also present on the lower surface of the left wing tank but barely visible because the left engine nearly obscures that particular wing surface area. You will notice the absence of frost on the left side of the CWT as well though.
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