The Wikipedia article for Munjor, Kansas (linked in the profile) seems to indicate that the individual who founded these cities in Kansas was a descendant of the Johann Wilhelm von Monjou you mention above. So I don't think we can attribute the founding of cities in the 1800's to him.
However, the profile does seem to lean towards being the right time period for Johann Wilhelm, and not Otto Friedrich. I would have to agree that there appears to be some conflation going on between likely a Johann Wilhelm born probably 1727 and a Otto Friedrich born probably mid-1800's.