No opinion on whether the US did it.

But Hersh's essay indicates there were last-minute changes to the detonation method. That adds risk, which could have manifested as failure of some detonations.

Then the explosive charges are still there, and Danemark and Germany can recover them.

Why wouldn't be sloppy? Remember the Afghanistan pull out? The US is capable of screw ups. Unless of course people were falling down from planes and busses with kids and women were droned tactically?