(I'm not a light expert either)

To really compare two light sources, you need to look at the spectrum. But the spectrum is difficult to interpret because of the complex intrinsics of human perception. CCT simplifies this by mapping a spectrum to a single point on a curve, representing daylight. It allows you to compare two spectrums with reasonable confidence (in the context of the curve).

This curve covers only a small subset of all possible colors. Of course, mapping to it introduces an error (the original color is replaced by the most similar daylight color). But since photography flash modules try to imitate daylight anyway, the error is small. Within these limitations, CCT numbers seem to be an easy way to compare flash color.

Don't let the color issue distract you too much. In the end, color is a subjective topic. There should be harmony between camera, flash, driver and usage pattern. The blue decoration on the N900 backcover results in a blue cast on photos and shows that the original design was not perfect either. Imitating it may not be as important as you think. You could pick any popular camera reference design with good reviews and call it done.