It's the early 1400s in my Byzantine game now. After crushing those upstart Turks (Roma invicta!) I noticed that, shortly thereafter, my stability rapidly went to poop. I noticed that, even though I didn't control any cities outside my historical range, my expansion score was -34 (!). Upon investigation, I found that under my civics, it wasn't even running Subjugation (the default civic for expansion). So apparently my government had... no policy on expansion?

A timely Golden Age from getting the second UHV goal managed to save me from utter collapse, but the expansion score still hasn't gone up, even though I've switched it to Viceroyalty now.
EDIT: Just hit 1450, but the third ability didn't trigger, even though I'm certain I have three cities in each of the prescribed regions: Athenae, Dyrrachium, and Singidunum in the Balkans; Hierusalem, Ctesiphon, and "Armenia" in the Near East; and Carthago, Tripoli, and Hesperides in North Africa. I'm not sure that Armenia is in the Near East. Is Alexandretta? Or the Anatolian cities? Where exactly are the boundaries for the Near East defined in DoC?
EDIT EDIT: Nevermind, founding Susa got it. Just won an historical victory.

Let's see how much longer I can survive given my amazingly bad expansion score. (-44 now...)
EDIT EDIT EDIT LOLOLOL: It's the early 17th Century now. I revolted to the democratic civics to force a collapse, and now I'm taking back the parts of the Empire that I still want. Really, I only need the Balkans, Levant, and Egypt. Italy, North Africa, and the further reaches of the east aren't really worth the trouble. And if I may recommend something, perhaps the dynamic name for a Byzantine republic should the the Republic of Rhomania?