Taking up Clean32’s observation at #13, all of the eleven aircraft might indeed have been heading for the same place. For each aircraft the target is not specified – just named as DZ in all cases. All we get from the 501 is a selection of different routes to various points on the Indo-China border. I would have thought that the 501’s author would have numbered the DZs if they were different, even if he was concerned not to reveal their locations. Still I would agree that to drop all eleven eggs into one basket would be surprising and very different from the practice established with the Resistance in France.
I note that KH277 “Z” crashed well away from any USAAF operations, about half way between its base at Digri and its first turning point. It fell either after only a couple of hours flight or near to the end of its sortie – we do not know which. If it fell due to a night fighter attack, it kept airborne for several hours afterwards. In that case, with two W/Ops on board, one would have thought the aircraft would have informed the squadron of the trouble it was in.
The 501 tells us the wreck had been found behind XIV Army lines. It was probably found by a contingent of what was known there as V Force. Surely whoever found it would have reported any gun damage ? I suggest “Z” was lost by accident rather than by blue-on-blue.