Also been slowly brainstorming a city sim technical design on and off for maybe 7 years as a side project that has a few similar goals in regards to large unit counts and custom buildings so it seems we have similar interests there. It feels like it has a high risk of becoming an endless feature creep project, though, so it's been hard to prioritize as a focus until I can settle on what the soul of it should be which informs all other decisions.

Just guessing From what I see, it looks like you may have chosen a technical path that doesn't scale well even if the resource usage is reasonable at this scale (constant time != constant resource). There are certain features I want to have that I think your approach doesn't make viable, so depending on how your game evolves the algorithm may get in the way. You've probably already thought through some of that and figure with some optimizations maybe it will be enough for your needs. Might even have a little extra versatility in other ways.

Hope you find success! I'll keep an eye out on your project. One bit of feedback though, I would personally change the name. It's not fun to read and doesn't roll off the tongue very well.