Crazy excel project though, well done.
Back in the day people did ray tracing by hand on calculators, in PostScript (yes, the document description language used by printers), ... ray tracing is really simple, a basic exercise in vector maths, so we should expect to see it everywhere.
Is it for fun? If so, great. Not my cup of tea personally, but I can imagine how it could be someone's.
If not for fun, what is the point? It presumably isn't to create a usable ray-tracing system. Perhaps a challenge to improve the author's Excel skills? If so, I suggest they move on to a proper programming language and visualisation system.
There seems to be this obsession, among some people, with using Excel for all sorts of inappropriate things, and I have a sinking feeling that this might be related to that. A system for generating contracts using Excel formulas, in Excel, instead of using mail merge, or something else, with Word or something else designed to format prose text, is a horrible example I have come across at work.
I've never done anything that visually elaborate. But I have created data visualizations, using conditionally colored cells in large arrays.