I would be interested in the research you used to verify this. I have search for some time and had seen Sooneck Castle as a possibility. I haven't found any of the mountains mentioned (Rugesian). One would have to realize that the orignal researcher could have translated the name without umlauts etc for the mountains and also the Castle name.
The information speaks of George Reitenauer who was in the services of Rudolph of Hapsburg. The family of Rudolph I (1218-1291) of Hapsburg were of Swiss origin and upon the death of his father, Albert IV, in 1239 became Count of Upper Alsace. Rudolph's mother was Heilwic of Kiburg. By 1300 George was the only man in this family still living. At the age of nineteen he married Countess Isabella Fontenay, of French origin. George died in 1327 of wounds received in the Frierischon War, leaving three sons, Joschim, Tancred, and Bernhard. It is said that Bernhard carried off Anna Von Bauerheim, the daughter of Herman Von Bauerheim, Mayor of a city on the Rhine. Bernhard later married Anna and she died at the birth of their son Nicholas. Bernhard died in bed at a ripe age in 1374. Nicholas married twice and left four sons, Rudolph, Robert, Care and Ferdinand before dying in 1386 in the battle of Sempach. Care and Ferdinand went and lived in Thuringen. Robert went off to battle and no further word of him. Rudolph lived at Shadeneck castle.
One would need to also look closely for the mountains mention. You also find Koblenz on the Rhein at the present day German - Swiss border. This was all Germanic in the time the information is noted. It has mountains and Rudolph of Hapsburg Castle is very close in near Hapsburg and Brugg (South of Koblens). There are also remains of a Castle across the Rhein River.
None of this is to say this is the site but it has a lot of facts that come close.
I only wish I come see the exact referenced information in the original language. To give you a feel, my mothers family is "Damewood" but the oldest person we find is Hans "Demuth" from Schaffhausen. With the umlauts the name is pronounced like "Dam" "Woot"
I have several maps of Europe and Germany in ancient time and throughout out the years. The closest for the mountins was the Germanic Tribe called "Rugians" who were in the area South of the Danube River. Area is closer to present day Switzerland. (From the map " German Migration and Conquest 150 - 1066.
The Rugesian Mountains could have been named for them or they took their name from the mountains.
Very interested on any research for this information. I lived in Germany for 3 years and plan to visit in the future to do additional research.