Path Tracing Lighting with Cloud Colour Filtering

[WAS]

So, I think I may be encountering a issue, I am not positive. When I try to have a off-camera sunset bathing the direct lighting in colour, it isn't really working. I have the colour at max itself, then the intensity/amplitude of the colour to 5 so that the glow was nice and big and strong.

Here is where I see an issue, for such a strong orange, I get more or less the same colour on the direct lighting, a little more yellow. But the shadows where ambient bounces, is filled with the strong orange. The cloud is then masked by an inverted distance shader, so there is about 10000 meters of fuzzy zone in front of the camera, where you can see the strong orange in the haze. But why no colour on the surfaces? It's clearing very strong behind the camera, or should be. The terrain is just gray, so it's not adding any brown tones or anything.

Is this wrong? It seems like it's wrong. I don't recall seeing such a phenomenon. Is using a cloud not going to work like this in PT? I know the grain is bad, may do a better render overnight. It'll take about an hour or two, but still tinkering right now. But it looks to me like there is terrain highlighting from ambient that is orange, while direct is very desaturated.

[WAS]

May be easier to see in this one with exaggerated details (though I notice there are issues here with it and those spots, some weird green artefact) Tried getting orange-red even stronger

Interestingly, I also notice that the small ridge on the flat ground in the left area is a lot orange-er too in semi-direct and ambient light.

[Dune]

I'm not much help here, missing the middle spectrum of cones in my eyes.

[WAS]

Yeah I'm not sure. I'd figure that the shadowed areas would be picking up more skylight than direct lighting ambience. Maybe I'm wrong, but it's really proving hard to get bathed direct lighting that's red, and looks odd when shadow areas are redder.

[Dune]

In fact, shouldn't shadowed areas not be greener with red light? I know a painter who not only darkens, but deliberately intensifies the shadows with a stronger complimentary color, which makes the shadows very much alive.

[WAS]

That may be an artistic liberty, but the shadowed areas should be only picking up ambient from direct lighting nearby (which isn't nearly as coloured), and general ambient which should be sky.