Its actually just 4 channels. There is a percentage value that represents the color temp and those parameters just control the range. I prefer the direct entry of the Kasa bulb- its much easier to set my bulbs to 4000K than having to calculate that to be 34%.
Trying to get certain white temps using RGB (or really HSB values) has never worked which is why a dedicated W channel is used.
I’m wondering if this is a rebranded product like the sensor is? There are so many people with the same looking bulb and range that maybe that is the root cause.