Here are some images of the Park Tools pedal and cone wrenches showing their relative thicknesses and the relationship of the pedal wrench to the MKS pedal coupler.
While I agree that cone wrenches generally should not be used for other high-torque applications such as pedals or pedal couplers, there is at least one example of use of a cone wrench being successfully used for pedals. It is possible that there exists a pedal wrench slightly thinner, which would be suitable for these pedals.


On the left is the Park Tools cone wrench, next to its thicker cousin, the pedal wrench. They both seem to be made of the same hard, high-quality steel.


Park Tools pedal wrench thickness: about 4.75mm.


Park Tools cone wrench thickness: a bit over 2mm.


Here is the Park Tools pedal wrench on the flats of an MKS pedal coupler. It is clearly too thick for this application.