Well, there is no MIDI editor in V3 of KK yet so no chance to do anything until it is released.
However, it will likely only allow what was possible with the last keyboards and that allowed I think 6 key ranges to be set with a colour assigned to each range, you cannot select specific colours for individual keys.
If by "top keys" you are referring to the BUTTONS on top of the keyboard for DAW control etc, you cannot program these at all. You are limited only to the encoders and keys for MIDI stuff. Basically what you are expecting is not possible and I wouldn't suggest holding out much hope for that to ever change.
I would suspect such things would be driven from within the plugin that's loaded and active, not as an external signaling mechanism like MIDI. But who knows. Given that's only been demonstrated in conjunction with whatever object is active or from within a specific built-in capability such as the key assist, it's anybody's guess at this point how the light guides are setup. But I think since the light guide responds to whatever plugin is active, it's a pretty good guess it's controlled from there.
As far as top keys (assuming MID controls) you can do all of that via mapping MIDI responses.
