I was under impression those knight names mean land, i.e. Franz from Paula Schrank, but I cannot find any territory named Paula Schrank. Also, German wikipedia states he was Ritter von Schrank (Knight of Schrank), if Schrank was territory what was Paula? But was Schrank a territory, maybe it also meant something else?
His first name was not just Franz. Franz de Paula and Franz von Paula were given names, which came from Saint Francis of Paola whose name can be translated in to German as Franz de Paola. Although it seems that there are some variations in how sources put his full name e.g. Franz de Paula von Schrank, Franz von Paula Schrank or Franz Paula von Schrank, it is apparent that his surname was just Schrank.