Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
The brown could have been sun (tropical UV) burnt/faded/oxidised midori/green or a dark red or maroon perhaps, particularly if the colour was arrived at from b&w photo film/negatives - different WW2 era films types had differing graduations of colour into the b&w format AFAIK.
Loving the additional pics, infos, diorama images and kits guys