I get it.
thanks for the update.
my approach is that the product content is stored in the database, which will have the appropriate descriptions by language, this is essentially the dynamic part of the site, and using a sessionid dependant upon the subdomain used, the sql will filter the data accordingly.
the textual content of the site(s), such as the menus and some descriptive text is (presumably) going to be fairly static once set up.
more dynamic info, such as news etc would need to be in multi language form anyway, and could be driven from the database if required