They look great, however I think it would look better if the Central Europe background has one colour (so the eagle has the same colour as the rest of the background, or the rest of the background has the same colour as the eagle has now.) All the others have a single colour background and it looks better in my opinion. With the Central Europe set it looks as if it's a helmet or building on top of a blue background with some eagle trying to get between them or something.
The other sets look absolutely great, and other than the thing I mentioned the Central European set looks great aswell, I really look forward seeing the rest of the sets and the other UI graphics you've made!