As of March 24, 2006 at 5pm EST the 1.0X update of GalCiv II convert international users into the English version.
When 1.1 goes public, we will work with Paradox to get the new files translated into the appropriate languages.
The other thing we have heard is that some people have had problems graphically with non-English versions. We do not know the cause of this but we do know that you can fix it (until we find out the real cause) by:
Go to Control Panel. Open up Regional Settings. Change to English. It shouldn't make a difference in how your computer works. We don't understand why it makes a difference in a computer game either.