Somewhere in wp_trackback.php (string 71,72,73):
$title = (strlen($title) > 250) ? substr($title, 0, 250) . '...' : $title;
$excerpt = strip_tags($excerpt);
$excerpt = (strlen($excerpt) > 255) ? substr($excerpt, 0, 252) . '...' : $excerpt;
Function substr working properly only for english UTF-8 strings because codes of latin letters in ASCII same to UTF-8. But for cyrillic and other national symbols function substr works incorrectly.
I recommend replace all substr inclusions for language-sensitive data with function wp_substr():
function wp_substr() {
$function (function_exists('mb_substr'))?'mb_substr':'substr';
return call_user_func_array($function, func_get_args());
}
