Пробвах с кода отдолу в /wp-includes/formatting.php файла но нещо не се получава а за оскласс е перфектна
if (is_utf8($string)) {$chars = array(
"А"=>"a","Б"=>"b","В"=>"v","Г"=>"g",
"Д"=>"d","Е"=>"e","Ж"=>"j","З"=>"z","И"=>"i",
"Й"=>"y","К"=>"k","Л"=>"l","М"=>"m","Н"=>"n",
"О"=>"o","П"=>"p","Р"=>"r","С"=>"s","Т"=>"t",
"У"=>"u","Ф"=>"f","Х"=>"h","Ц"=>"ts","Ч"=>"ch",
"Ш"=>"sh","Щ"=>"sch","Ъ"=>"","Ы"=>"yi","Ь"=>"",
"Э"=>"e","Ю"=>"yu","Я"=>"ya","а"=>"a","б"=>"b",
"в"=>"v","г"=>"g","д"=>"d","е"=>"e","ж"=>"j",
"з"=>"z","и"=>"i","й"=>"y","к"=>"k","л"=>"l",
"м"=>"m","н"=>"n","о"=>"o","п"=>"p","р"=>"r",
"с"=>"s","т"=>"t","у"=>"u","ф"=>"f","х"=>"h",
"ц"=>"ts","ч"=>"ch","ш"=>"sh","щ"=>"sch","ъ"=>"y",
"ы"=>"yi","ь"=>"","э"=>"e","ю"=>"yu","я"=>"ya",
" "=> "_", "."=> "", "/"=> "_", "-" => "_");
$string = strtr($string, $chars);
}
if (is_utf8($string)) {$chars = array(
"А"=>"a","Б"=>"b","В"=>"v","Г"=>"g",
"Д"=>"d","Е"=>"e","Ж"=>"j","З"=>"z","И"=>"i",
"Й"=>"y","К"=>"k","Л"=>"l","М"=>"m","Н"=>"n",
"О"=>"o","П"=>"p","Р"=>"r","С"=>"s","Т"=>"t",
"У"=>"u","Ф"=>"f","Х"=>"h","Ц"=>"ts","Ч"=>"ch",
"Ш"=>"sh","Щ"=>"sch","Ъ"=>"","Ы"=>"yi","Ь"=>"",
"Э"=>"e","Ю"=>"yu","Я"=>"ya","а"=>"a","б"=>"b",
"в"=>"v","г"=>"g","д"=>"d","е"=>"e","ж"=>"j",
"з"=>"z","и"=>"i","й"=>"y","к"=>"k","л"=>"l",
"м"=>"m","н"=>"n","о"=>"o","п"=>"p","р"=>"r",
"с"=>"s","т"=>"t","у"=>"u","ф"=>"f","х"=>"h",
"ц"=>"ts","ч"=>"ch","ш"=>"sh","щ"=>"sch","ъ"=>"y",
"ы"=>"yi","ь"=>"","э"=>"e","ю"=>"yu","я"=>"ya",
" "=> "_", "."=> "", "/"=> "_", "-" => "_");
$string = strtr($string, $chars);
}