Sorry if this is the wrong section but it sounds like it's too 'under the hood' for GD. A couple of friends and I enjoy casual FA play against Sorian AIs and we've created a mod that both spawns some units and has an itemized list of T4 unit restrictions that we use to keep Sorian on a short leash. When I create an FAF game I see my mod in the list, but the unit restrictions aren't available. The unit-restrictions part of the mod has a UnitRestrictions.lua file and some other stuff which enumerates a set of restrictions. This works by taking advantage of a Lobby Enhancement Mod feature that scans the active mods for these enum definitions and adds them to the main list, allowing one to create additive lists of restrictions across various mods.
From reading over patch notes it sounds like FAF doesn't work with LEM since it's got its own way of doing things, but is there similiar functionality in the FAF lobby?