Yes this is exactly it, great terrain, but yes, desaturated. I don't know about modding but I know about optics. Satellite imagery is altered by season, time of day, weather, climate activity, etc etc etc... all which impact the light quality. For example, go on Google Earth and look at the Korean Peninsular, which has been highly mapped, but every stretch of imagery is different to the next, you can also see snow covered sections next to plush green wet season sections next to dryer hot season sections... this would be mere so for South East Asia, where provincial differences between wet and hot seasons are huge. So in these tiles you get the odd effect ofg plush jungle that ends right next to very 'blue' unsaturated tiles that look in the sim like peak hot season on a hazy day.
To correct this I suggest looking at images and photography from the ground from Vietnam, throughout the regions, terrain types and seasoosn to get a proper feel of the tonal range you should be aiming for. I will look forwards to seeing that work. If anything I'd say the earth should have a mostly red hue for many lowland regions.