Working with watercolor pigments can be risky because they often contain preservatives which will "poison" the gelatin with crosslinking. It's
also difficult to acquire them in consistent volume or sufficient purity. We once had a very skilled local carbon (not carbro) printer who used
them, but just for small prints; and he was, by any measure, certainly a starving artist, who relied on donated products and used his own
tenement bathtub to develop the images in. There are a number of good technical resources for color carbon printing, including the people originally involved in Ultrastable and Evercolor, Todd Gangler, and Sandy King, who host a whole forum dedicated to carbon printing of various
sorts. Carbro per se is going to be trickier for you to resurrect, but people keep trying. But back to pigments - powder pigments used in the
auto paint trade are generally going to more lightfast than those in art stores, and Richard Kaufmann once published a list of the ones he
used back then. I have been dabbling in the subject and have a good idea of the holy grail of these things, which if it ever arrives, will involve some radically new industrial technology, way above the league of photographer per se to invest in. But there is some hard research
money going into it. ... the point being a set of truly transparent pigments, and not dyes, lakes, or opaque pigments. But that's an involved
story, and you're going to have to do a LOT of homework to get any of this cat in the bag.