I contacted - Heraldische Gemeinschaft Westfalen (firstname.lastname@example.org
Michael Waas M.A., B.A. Chairman and Herald Westphalian Heraldry Society (registered society)
So far, no known coat of arms has been found for Ohrndorff, Ohrndorf etc.I did learn that Hof Ohrndorff was a Royal Estate:
"The "Manor" Ohrndorff was a so called Koenigs-Gut (King's Estate). Such Gueter (manors) were free from taxes etc.! In early times Germany had no capital and the King/Emperor and his court always was on journey through his realms. To maintain and support the court shattered over Germany were so callled Koenigs-Gueter. There the court could have a break or a longer rest. Administrators of the Gueter were Lord-Stewarts often called "Graf" as Gograf (modern German "Gaugraf")! In the 16th century Koenigs-Gut became less important and were sold to the administrators or to other noble families. By the way if there would be a family arms it must show the Imperial Eagle. Imperial places always were displaying a kind of an eagle.
I sent him links to an online coat of arms vendor and he said:
Beware of the arms-mongers. Companies selling those arms are fraudsters. The alleged Ahrendorf arms belongs to a family "von Wahrendorf" , the Orndorff arms belongs to a family named "von Dorndorf"! Both families are orginated from the Baltics (Livonia).