DID shade of Luftwaffe tropical uniform is the more close to the real thing you can get, these where quite regular on cloth shade of color most of the time because it's Luftwaffe contrac manufacture where in lower numbers, the other 1/6 brand shade is to dark and sadly is incorrect, in fact looks more like a color seen in Kriegsmarine tropical clothing sometimes from French manufacturing or tailors, the Luftwaffe tropical tunic and pants where a particular design and also produced in fewer numbers than the other two main armed forces branches, also style and details quite different from the army HEER and Kriegsmarine tropical line of uniforms wich indeed had quite a bit of color shade variations depending on manufacturer and area of production.
Even the Italian "SAHARINA" tropical tunic that was issued and used mostly by the Waffen-SS, was very close in shade to the Luftwaffe issue one, never the "toasted tan" color variation.
I can't remember where I saw it, and wish I'd saved the reference in my list of figures as I often do. It described variations in the shades of cloth, with one being much darker - which gave me heart considering the colour of Ujindou's figure.
The closest thing that came up since reading your post is a description in Osprey's
Luftwaffe Air and Ground Crew 1939-45, though it refers to the standard colour rather than a variation:
"...Luftwaffe Tropenanzug was of a more traditional
orange-sand colour - at least when new. The combined ravages of African sun, dust storms, heavy sweating and frequent washing (often in petrol, marginally less scarce than water) all took their toll, and some items became bleached almost white."
The Ujindou colour is hard to describe, but "orange-sand" would fit the bill.
It wouldn't surprise me if they were off the mark, because the camouflage parts included with him were garishly bright, and I swapped them out on my second figure with spares from DID's Fallschirmjäger.
This is a uniform advertised by a company who hires out props for filming etc. There's no description about its source, so I assume it's a modern reproduction of what was meant by "orange-sand", and is a shade lighter than Ujindou's, though the cap is actually very close:
https://history-making.com/product/luftwaffe-tropical-uniform-private-basic-uniform/
Ideally I'd like it lighter, as he stands out so much from DID's.