2D inkjet printers... and advanced fine art reproduction
... only basic and office models use four inks. Entry level prosumer photo printers usually use at least eight, and pro models 10-12 inks.
What they did was also already made, albeit with more sophisticated imaging systems:
It looks the novelty of their approach was using AI instead of more sophisticated 3D imaging, but I think from a simple 2D photo it could miss details. Correcting colors for light conditions is something photographers learn early, from simple white balance to more complex profiles - even if today sometimes it is complicated by non-continuous spectrum lights.