You're right, of course Dave, that there's an historical kernel--as there is for The Waltharius, Beowulf, the Tain, and the Song of Roland, among others. But the current form of the Nibelungenlied is more than half a millennium after the characters whose stories it transmits and there are some serious anachronisms and inconsistencies...

To make a decision about the red gold in the original MHG you simply have to look at the original language, the connotations of the words involved and the usual or unusual noun-adjective collocations. Malcolm Douglas's fascinating information about translation-ese is relevant for the English....

A parting thought: it has been said that treasure was to an early medieval audience as sex is to a modern one. What the audience of the date of the earlies Nib. manuscripts thought about red gold is yet another questions.