If you take a close look to this picture you will understand how I reduce RGB brightness for [blue violet] color.
concerning the WW (Warm White) and W (for Cool White ) they are separate LEDs that Magic Home can control with a 5th Wire present in the RGBW models.
About HSV to RGB , Amazon Echo send color in this format also GH use another technique for colors.
Pls. read here:
[HSV to RGB] How to use Google Home + Blynk with ESP8266 { without " IFTTT " }
You can test Amazon node by saying “turn room to green” and take a look to payload.
payload: object
hue: 0 // Amazon Red color
saturation: 1
brightness: 1
{"hue":120,"saturation":1,"brightness":1} // Green
{"hue":240,"saturation":1,"brightness":1} // Blue