Is the AH3 engine able to do whitewash white as well? I’ve heard there are some issues with white and was wondering if that is why you chose a silver subject.
It's definitely possible. The issue with the AH3 lighting is that light and bright colors tend to wash out and glow when in direct sunlight. The remedy is to draw those items on the diffuse maps with dull tones and let the game engine brighten them to their realistic levels. Since white is both light and bright, it requires using shades of distinctly light gray to look like realistic white paint in game.
For example, this is a a whitewashed 109G-2 that I just finished.
I think you'll agree that the whitewash looks realistically white in game.
Now, here are the colors I used with actual pure white (RGB 225/225/225) and pure neutral gray (RGB 128/128/128) to show how much closer to neutral gray you need to make white paints to appear well in the game.
Colors left to right: pure white, insignia white, whitewash white, pure neutral gray
This is what happens when you use white that is too close to white...