In my experience outside the US with XP and Pub2003
Starting a publication from a template that was installed as part of
Publisher (made in USA) then the language for existing text boxes will
be US English regardless of the regional settings in your control panel.
New text boxes in a template will assume the language set as detailed
below.Changing the language of existing text boxes to Local and saving
the publication will make the language for THAT publication Local.
If you start a blank publication then add text to it, the language will
be decided by the Regional settings > Languages >Details > Default Input
Language.
John G.