It makes one wonder how an engine power delta (deviation) could lead to cyclic control problems. No doubt they were there as it would take some motivation to put down at night in cold rough water rather than continue to land which was not so far away. As you rightly say....there are so many hours on the fleet it should be a well known flying characteristic if it were common to the aircraft.
One has to assume the engine problem and the flight control problems did not have a common cause as they are two very different systems.