Languages on Heroku

Hi,

When I create a Plone site on Heroku (using https://github.com/collective/training-sandbox ), whatever language I pick, the site is in english.
If I install plone.multilingual and add several languages, the Plone interface remains in english whatever language the user chooses.

I know Heroku only provides english locales (see http://stackoverflow.com/questions/11486133/python-locale-settings-on-heroku ), but I do not think it should impact the Plone language in any way, right?

Does Plone have permissions on file system to compile the po to mo files?

Nice catch! Thanks!
Now I need to figure out how we allow it.