If I understand right your problem, you can use external
XML files, dictionnaries, containing the actual translated
sentences. You'll access them via document(), for example
document(concat('i18n/dico-', $i18n-lang, '.xml')) where
$i18n-lang is the language name, for example 'EN', selected
in your input document, and the 'i18n' directory having a
file named 'dico-<lang>.xml', a dictionnary, for each
supported languages.