Hello! I've discovered a little problem: At the creation of a new site the site is created using only the standard_index.html_en not using the index from the selected language in the admin interface. This is a small problem but it exists. Thanks for your work!
Thats no bug. the language used for the files is set in the file /usr/local/ispconfig/server/lib/config.inc.php and not in the interface. The variable name is: $conf["language"]