When using chat in other languages some printings call userdate() without fixing locale
example of location : mod/chat/report.php ยง169
adding the marked line fixes the issue and make userdate print in the correct locale.
else {
$sessionstart = $lasttime;
if ($sessionend - $sessionstart > 60 and count($sessionusers) >= 1) {
>>>> setLocale(LC_TIME, substr(current_language(), 0, 2)); <<<<<
echo '<p align="center">'.userdate($sessionstart).' --> '. userdate($sessionend).'</p>';
print_simple_box_start('center');