Those two young gods tracks are from their great Young Gods play Kurt Weill album.. The only album containing tracks where Franz sings in German IIRC. It was released after they played a Kurt Weill Festival, much to the annoyance of Kurt Weills estate apparently. So there is kind of a german link I suppose.
'Salomon song' is in the original German, 'Speak Low' is in english. But Speak low is probably the weakest track on that Kurt Weill album, should have gone with 'Seeräuber Jenny' or 'Alabama Song'.