mitsho
Deity
I'm not worried it will be unbalanced. I'm worried about Austria being made into something they shouldn't be.
You wouldn't, for example, want Nepal (if they were in the game) to have a unique ability which allows them to build an awesome navy, would you?
Sure, it might be a good ability, and a good reason to play as them if it's balanced, but it wouldn't make any sense right?
Another example would be: Give the Huns the ability to spend gold to complete a Wonder. Might be balanced, might be nice from gameplay point of view. However, it would undermine Egypt and make no sense at all, considering the flavour of the Huns as a barbaric warmongering civ.
Likewise, with Austria. Nice UA, balanced, good gameplay. But used inappropriately with no limit to acquiring city-states overseas, this would turn them into a colonial power undermining the English, Spaniards, and Dutch.
I'm not going to say the same thing again and again, so will stop here.
I do see your point, but I do think it's a nonissue. Yes I can see how that would have been a good UA for say the Portuguese, but it works as well for Austria. I don't believe forcing them to play "contiental" every time would be a good idea. Options is what makes the game fun. Even if you can play the Austrians as warmongers on different continents (and btw. the UA allows you to neglect a navy or ever building a port

And btw. your hun example shows that you can never go around that problem. Their production bonus and tech advantage basically means that they are the fastest in building a wonder, if they want to. Wonder rushing will be a strategy for them, not really historical. Their UA which was designed for early rushes can be used totally different.
Also the Ethiopian Turtle UA basically allows them to conquer the world more easily if they ruthlessly burn down everything but the capitals...
We can do that in vanilla as well if you want. Historical "Realism" is a goal but minor offenses like the Austrian Colonial Empire aren't that bad. Oh, and btw. I present you Maximilian I. of Mexico, eh Austria.