I may be missing a point here, but I'd have thought that a Nazard and Tierce would already be tuned to “pure, non-beating intervals”. The only exception would be on an extension organ, such as a theatre organ, where separate ranks were rarely provided for mutations.
Random detuning and the wind model would only introduce a degree of randomness which corresponds to that found in a pipe organ, so leaving those parameters as supplied should produce the most natural sound.
The Wikipedia article is helpful:
https://en.wikipedia.org/wiki/Cornet_(organ_stop)
It states that “The 8' rank is stopped while the other ranks are open”, so that might be worth thinking about – stopped flutes seem much more common than open ones, though maybe that depends on the period in which the organ was built, and the repertoire it was designed to play?