Nvm yall, if anyone else is wondering how to edit this element of the game (mind you it is "unbalanced") It is located under data/scripts/library/libBuildLimitGroupTable.lua. It can be edited with Notepad++ like everything else you're used to.

A better question would be "Where are the ground company XMLs located if the ones in the XML folder are vestigial?" or "Why does the normal procedure for modding the ground battle unit cap yourself not work in this mod?"

I've been going through the xml folders again and again trying to effectively copy the Legions+ mod's functionality on my own, but the usual tricks to increase the land battle unit cap and to remove vanilla build limits (not the scripted ones, the regular ones that are part of the ground company data) don't work because of the weird file organization and I'm stumped because it almost seems like the mod is somehow storing coding in thin air.