Mark Fairchild, one of the authors of CIECAM02, recently published a paper that heavily simplified that equation: https://markfairchild.org/PDFs/PAP45.pdf

If the link doesn't work, the paper is called: Brightness, lightness, colorfulness, and chroma in CIECAM02 and CAM16.

Also, if you want a readable introduction to color science, you can check out his book Color Appearance Models.