As a traditional illustrator and a passionate Krita user, I find mind-boggling that after so much discussion and the availability and interest shown by its creator @rvanwijnen, spectral mixing has not yet been implemented in Krita.
That said, I would like to recommend a little known plugin that makes spectral mixing (using the spectral.js library by Ronald van Wijnen) readily available within Krita – Colorplus by @seguso
