I 've done a lot of vintage German drumkits and there is not always an obvious reason why one piece of wrap cracks, fades or disintegrates. Sometimes it's the colour itself, sometimes it's the storage conditions and sometimes it's the production run. A case in point is,the bass on a Gold Pinstripe Tromsa kit I sold about a year ago. Like most bass drums it had a strip on the bottom, where the wrap didn't make it all the way around. The entire drum's wrap was oxidized and covered with myriads of little cracks. From a distance; it didn't look too bad but up close you could see the ravages of age; the strip on the bottom---clearly cut from a different sheet was almost like new.---and it wasn't due to being on the bottom and away from the light because the demarcation between bad and good was the seam of the two pieces of wrap. Clearly the one sheet evaporated, dried out and oxidized , when the other didn't.
Turkis Flitter from Deutsche Celluloid is what your wrap is and it does seem to be one of the fadier colours. Light is a factor, bleaching the colour but so is oxidation, of the metal particles in the wrap--darkening the sparkle . If you look at the wrap, closely----it probably has a lot of little tiny cracks. This is due to drying of the solvents in the wrap. That said, I have a number of drums in my possession wrapped with the very same wrap that are almost mint. Some dating from the 50's, so it is a sheet to sheet thing.
Your kit has the old polished aluminum lugs and cast aluminum T-rods and claws that Deri used for a while and they are in good shape. The drums would really benefit from a rewrap. Having been around the type of wrap you are dealing with a lot, I think they are way beyond any potential vintage value based on originality. There are lots of options too. Deri used most of the sparkles of the day as well as oyster, ripples and pearls. You could bring life to them with a close to authentic rewrap. You never know---you might even find some N.O.S. sheets of Deutsche Celluloid wrap. I've seen them sold and have pinched myself for not buying them.