This is supremely exciting, thank you for working on this. I also immediately thought of Iroh for networking (nit: though I do think you could include the port in the copy-pastable player id).
Using Lua files for AI does not seem like a great idea if you have control over the game source, though you can likely run run one lua thread per AI player.
I wonder how much your project is an attempt at a faithful reverse-engineered version vs an improved one, though given that you improved on networking, I would guess the latter? There are many features I would love to see added in, such as multi-monitor (multi-window & multi view) support. My concern is: as you diverge more and more by adding features, you risk making it harder to compare to the original for accuracy.
Anyway, as I failed to install FAF in my Flatpaked Steam install a few years ago [1], I would really appreciate a native Linux build for this (though I guess I could try the .exe under Steam/Proton).
I also played a bit of Supreme Commander on my Steam Deck, and while it was playable, I would appreciate better controller integration (at least Steam Input to simplify UI overlay creation).
All of that, and more, would be doable with a decompiled port.
[1] It would have been possible, I needed to shoehorn a java runtime in there, but it didn't sound fun anymore and only had a few hours to play with friends