Not true! The appearance of dyes under different light sources can be easily calculated, so long as you know the spectral reflectance of the dye (as measured with a spectrophotometer), as well as the spectral power distribution (PSD) of the source. Multiplty these functions together, then multiply by each of the CIE standard observer color matching functions. The integral of these results will give you the XYZ tristimulus values, from which you can calculate the chromaticity coordinates, L*a*b* values, and so on.
Thinking about this makes me wonder. At present, the new EK POD units produce color images with a huge amount of metamerism between daylight and tungsten. So, someone there doing R&D has not gotten the word on this method, or they are ignoring it, or they have note even tested for it. It is truly amazing. We used to do these tests without computers and thus without the intense calculations you describe. Being in the Flower City yourself, you must have some experience with this yourself.
One of our great EK color engineers died last week BTW.