It's not really darker because of any complex color science so much as the top of your test chart is literally darker in shadow. So that makes everything on the test chart pretty much impossible to evaluate.
There's certainly a shift. I can't say if it's the dragon sensor or the light since I don't have either to really tear into and test. Also unfortunately Nuke doesn't support Dragon yet, so I can't use a real linear-light surgeon like Nuke to build try and reverse engineer a LUT to precisely figure out what's going on. Here is my intuition though from looking at it in RCX.
1st up, just to get this out of the way, a large part of the reason why you're seeing such a shift in color on your cambook is because your light moved. Once the lighting changes everything is up for grabs.
I would expect the closest match at the Hexolux "correct" values of 5300/3200. But if I clear out the RAW settings and try to debayer at 5300/3200 I see some red starvation in the daylight and some green starvation in the tungsten. (both are yellow tinted pretty strongly). Once you're red or green starved all of the color science is going to be off from there. So the question is, is the slightly color starvation a sensor anomaly or a CRI issue. That I can't answer without trying a few different lights under more controlled conditions. I'm inclined to say the slight shifts in neutrality are color science related not light related. Most useful though would be to redo the test with a bit more control. In a perfect world there would be a perfectly neutral set of polarizing film for the light and a really high quality linear pol on the lens to eliminate all specular highlights but just better controlling your consistency would be a good first step. When compositing the first thing I always look for are analagous neutral samples and you have that in the edge of the cambook which is medium gray but is very dark in one test but relatively bright in another. Once you run it through REDGamma those slight variations in luminance are going to be magnified from the S curve. If I match the luminance on the top of the chart (where red is) I see very similar saturation. If turn off the gain on the top of the chart the colors darken and as you would expect by definition will increase in saturation.
Primaries are very very sensitive to exposure. Take this for a thought experiment and it's easy to see why. If you have RED you have R: 1.0 G: 0.1 B: 0.1 If you want to increase brightness one stop you would technically end up with 2.0, 0.2,0.2 but since we clamp to 1.0 for display what you actually get is RGB 1.0, 0.2, 0.2 You've halved your saturation. Things get even more extreme once it gets run through a gamma curve.
