Those sorts of Excel projects generally aren't available in open source (or source-readable) projects. My first "real" programming job was to convert an Excel

Those sorts of Excel projects generally aren't available in open source (or source-readable) projects. My first "real" programming job was to convert an Excel based report into one done with a general purpose programming language (we chose Python) because the reports were taking hours to generate in Excel and each report file was over a gigabyte in size. If it were simple static reports it would probably have been easy, but minor modifications were necessary every week, and the analytics team was terrible at conveying what was actually required without actually doing it in the excel, so management decided our program had to generate a more optimized version of the original Excel file as output to give to the analytics team to then work on. After like 3 months of work on this, I figured out how to just write a tiny python script to remove the unnecessary data from their excel files. It made it so they could open it on their cheaper laptops without grinding to a halt and generate the modified report in few minutes. And we didn't have to try to replicate an Excel formula structure that had been iterated on for over 5 years into python, and our team was moved to better tasks. I've also worked on complex language localization projects that probably would have been most optimally handled by a database connected application, but it's way easier to send an Excel file to contracted translators, so that's what we used. I've heard other horror stories from friends who work in finance. But they work, so whatever.