Great nonetheless, and not to take anything away from the project, but I guess what I was expecting from the title, however ambitious, was an Excel-native solution.
I've heard legends of people fitting shallow feedforward NNs with pure Excel formulas.
I once interned for an economist who was using recursive Excel formulas for some kind of iterative optimization algorithm. I don't remember what it was, probably some iterative least squares thing.
I also was a research assistant for an economist who fit linear regressions with hand-written routines in Matlab. For some reason they felt more comfortable using Matlab's QR decomposition instead of just using the built-in linear modeling tools in R or even Stata.
Some people just want to use their favorite tool even if it makes no sense to do so.