I will gather them all and include them in further releases of the plugin.
You can find instructions on how to create your own translation in the included Readme. There are also 2 example locales included (English and Spanish).
I've created a french transation (attached to this post).
If the fr.php files not work:
Delete the locale_map.ini from /cache folder.
If that does not work, update your locale to the latest (fr-FR is now just fr)
Thanks for the translation @K17. I will include it in the plugin if I upload any updated version. Meanwhile, anyone interested can grab it directly from here. Just unzip and drop the new locale inside the plugins/OldDiscussion/locale folder.