You forget the reference material in Starlancer. Four coalition nations are canon. Russia, the Eastern Republic, the Tigris Confederation, and the East Asian Federation.
Russia is straightforward, the others aren't. Also, it wasn't stated those were the only four. They were just the only ones mentioned. That's not the same thing.
EDIT: I don't have the bonus DVD. One of you that does, could you send me that file, along with anything else that sheds light on the pre-exodus Coalition? It would be a really big help to us in getting the story straightened out.
EDIT THE SECOND: Also, that list of Alliance nations was incomplete, too. France and Italy were both confirmed to be Alliance nations, and I'm fairly sure that Australia rounded out the pack. Aside from mentions of the French and Italian fleets in the opening movie for Starlancer, one of the Alliance fighters has French and Italian markings on it.