By the way I stumbled upon the same problem a couple of days ago: the espmilight binding also uses a 0 - 100 range for the temperature. I still wanted the Kelvin value to be displayed and it can actually be done conpletely in the widget code: https://community.openhab.org/t/light-widget-with-temperature-control
You may of course stick with your version, I don’t see any disadvantages besides the additional item.