I didn't get to work on this until yesterday (Saturday) and most of today (Sunday) due to a crazy work week, but on the whole, I've very happy with my progress and final result. I had to cut a few features I had planned in my head, but I was able to implement the core feature that I had in mind. I originally named in LRCalc because it was going to feature a "Left" and a "Right" calculator that you could use to swap values, but I got the idea on Tuesday to make a calculator where you could just reference other calculators and this was my final result.
This was also my first time using Microui and it was quite nice.
I've uploaded the code to a Github Repository here.