Thanks @anon640257! I had actually asked this on the Vera community and got a similar answer. It looks like actually using D_DimmableRGBLight2 allows you to retain the white temperature values.
In the end, I was seeing some serious lag with Inovelli bulbs on Vera, and ended up moving all 60 or so Z-Wave device to zwave2mqtt with an Aeotec stick. I have been very happy with it – my bulbs are all lightning fast now. I used the manual setup described here to do so, which works super well.