Where are language files ?
In this example with 4 languages, the languages files (with suffix .po, .mo) come from the 2011 theme of the packages of latest version of WP for each country. It is not very easy to find but wordpress.org offers links for each. Because, these files will be modified for the site, they must be upload in the sub-folder langs of the child theme. xili-dictionary is the plugin to use to add or modify some terms of these files. Because the 3.2 release of WP is recent, some translation files of 2011 theme are not yet available.