From what I know this is a issue that persisted since the first Warhammer game. The Southern Realms of Estalia, Tilea, and the Border Princes, are not coded the same as the Empire. Which might have been a intention of CA to eventually add them as their proper factions, or they just never considered people would ever want to play as them. But regardless the Southern Realms don't have access to all of the Empire units, they don't have tech trees by default, and they don't have access to any of the Empire mechanics. Even looking at their files when doing any modding, they aren't even listed under Empire categories for certain things.

So unless Mixu goes and manually changes/enables all these elements for the Southern Realms, I would simply recommend not playing as them. Because I doubt Mixu or any other modders are planning to make those changes since Cataph will be (hopefully) releasing his Southern Realms mod in the near future (which for anyone who doesn't know, basically implements entirely unique lords/units/mechanics/etc. for those factions since it seems like CA has basically forgotten about them).

As an alternative, I'd subscribe to one of the mods that allow you to change your starting province, and take a faction like Hochland (since they usually get steamrolled by Festus anyways) and just a new game with them in the original place of where the Border Princes begin.

引用自 Provocative & rude：

outposts are glitchy and look like nothing and do nothing

I completely solved this problem, in my submod for Mixu's Unlocker - MIXER. Look for my submod in steam by key: "South realms aka Tilea, Estalia and Border princes"