Your server operating system is Debian GNU/Linux.
Your site uses utf-8 encoding. You have to convert the JEvents language files from iso-8859-1 to utf-8.
Convert the file .../components/com_events/language/french.php
Do not store a BOM (Byte order mark for utf-8 files) at the beginning of the language file(use babelpad or notpad++).
To get the correct date string which is now in English, you have to find the correct locale.
Look at
http://www.cultuurraadbever.be/administ ... hecklocale when you are logged in and you'll get a list of available locales on your server. On my system you would use fr_BE.utf8
Post the list of locales here