So, white mode can go a lot dimmer and a lot brighter than color mode. Which is weird, but makes it a lot more difficult to control via HomeKit, which only engages the color mode and not the white mode. Is there any fix for this?
Currently not. Homekit doesn’t support color and color temperature co-exists, so as the device, we can’t tell what the user really wants.
Is there a fix for maximum brightness and dimness not being available in color mode?
No, at least not recently. In our system, only when we know user wants to control the white light (color temperature mode), shall we apply some special lights mixing logic. Since homekit can’t give us the hint, we could do nothing, but just use normal color mixing algorithm.