Might be worth pasting the camera renders, which would give you a clue as to when the colour is being affected. I don't know Evolveds shaders and demos too well, but I imagine that there's a lighting shader, shadow shader etc etc, so it might not necesserily be the terrain texture shader that's causing the issue.
Maybe the lighting shader is using a reddish light for the sun. Another option would be to try disabling the lighting shader, and other shaders apart from the terrain shader, and see which one is browning the render.
I got a fever, and the only prescription, is more memes.
