Deprecated: Function get_currentuserinfo is deprecated since version 4.5.0! Use wp_get_current_user() instead. in /var/www/html/wp-includes/functions.php on line 5383
This is indeed a bug, thank you for reporting. To fix it, please download the file here, unpack it and upload into the theme folder, replacing the existing “comments.php” file.
Please download the modified template files here and re-upload them into your theme folder, replacing the existing files. This will allow setting the date format in “Settings – General”.