Krita uses KDE's color-schemes, and we can add our own as well. However recently I'm testing Krita from Ubuntu's Snappy, and aside a lack of integration (most noticeable the mouse doesn't follow the user's chosen theme) it's not possible to import custom schemes. What I'm trying to say is: in the same way we can import now bundles, we should also be able to import and manage our color-schemes. Not that Krita's default color schemes are bad, I'm just saying because some feel more comfortable drawing with a custom color scheme.

Yes, that broke with the port to Qt5/Kf5. It needs a bit of coding, and for that we need volunteers. It's not hard and probably would make a good first job.