...and another thing: "Pulling Power Back, "Easing Throttles", "Retarding Throttles", "Throttling Back" "Reducing Power" will ALL cause less fuel to go into the engines and therefore less power produced. In the intended context that is what happens. Whether it will result in more fuel usage per Nautical Mile was not a mention in the context nor intended. I hope that is made clear.
The idea that you have put forward, that reducing power will reduce fuel consumption is correct for maximising endurance, ie time in the air, but incorrect for best range, ie getting as far as possible with the fuel available in the tanks.
Leaning the fuel/air ratio to allow for the thinner air at alt will achieve a chemically balanced or stoichiometric ratio of fuel, which will result in reduced fuel consumption. This has nothing to do with wind.
Reducing, easing etc throttles will reduce power, and subsequently reduce speed. Whilst this will reduce fuel consumption/hour, the reduced groundspeed in a headwind means that the duration of the flight will be longer (compared to no wind or tailwind) and therefore the fuel consumed over a given distance will be greater. (Due to the fact that the aircraft is exposed to the headwind for a greater period of time.)
Otoh, increasing throttles (power) and flying faster in a headwind will reduce the time that the aircraft is exposed to the headwind and therefore reduce the overall fuel consumption for the entire trip, compared to flying slower. This is demonstrated very effectively in the charts above, and the physics would have been well understood at the time.
The idea that trip fuel can be reduced, or that range can be extended by reducing power in a headwind is incorrect.