People often use capital and seat of government interchangeably but they're not the same thing. A capital is the most important city -- it does NOT have to be where the government sits, even though most modern countries today (the Netherlands is an exception) treat them as the same thing (hence the confusion).
On the contrary, it's not uncommon at all that ancient empires had itinerant cities. China, for example. There was one preferred capital city, but the habit of kings to build new cities (like the Persians did often) made it so every king could choose from a number of palaces all in different parts of the empire, and if they were energetic managers, they'd use them all.
This is why I distinguished between capitals and seats of government -- or court cities, if you like. The Chinese imperial court may have shifted between Luoyang and Chang'an and a few other places from time to time, the Persian kings may have decided to hold court in Susa, Ecbatana, Babylon, or Persepolis as the desire (and season) suited them, but that's not the same as a "capital" city moving -- that's the court-based organ of government.
Similarly, for the Romans, we often hear of the tetrarchic "capitals" which is also not quite accurate. This, too, accords well with the Persian or Chinese model of the emperor moving his court and bureaucracy along with him for ease of control -- but under Roman law, there was only ever one capital with one Senate (Rome) and eventually a second capital (Constantinople), distinguished precisely because it received an inferior imitation (and eventual parity) of the capital privileges of Rome.
We know the Calradic emperors were appointed to handle wars (like Roman dictators) and that their positions eventually ossified into permanent ones. We knew they moved their base of operations to whereever was conveniently located.
That doesn't mean, though, that the Empire lacked a "capital" -- a "most important city." You can move the court and bureaucracy easily enough -- cities themselves tend to be located physically for a reason, though, unless you're nomadic. The question of what original city the Empire came from and what their most major settlement was is still left outstanding, although Baravenos is certainly a candidate for it -- whereever the heck it is.
