Steps to reproduce the issue

Add the "public static function transliterate($string)" block to language\en-GB\en-GB.localise.php to replace all accented UTF-8 characters by unaccented ones

public static function transliterate($string)  {
                $str = JString::strtolower($string);
 
                //Specific language transliteration.
                //This one is for latin 1, latin supplement , extended A, Cyrillic, Greek
 
                $glyph_array = array(
                'a'            =>   'à,á,â,ã,ä,å,ā,ă,ą,ḁ,α,ά,ā',
                'ae'   =>   'æ',
                'b'            =>   'β,б',
                'c'            =>   'ç,ć,ĉ,ċ,č,ч,ћ,ц',
                'ch'   =>   'ч',
                'd'            =>   'ď,đ,Ð,д,ђ,δ,ð,ḍ',
                'dz'   =>   'џ',
                'e'            =>   'è,é,ê,ë,ē,ĕ,ė,ę,ě,э,ε,έ,ə,ē',
                'f'            =>   'ƒ,ф',
                'g'            =>   'ğ,ĝ,ğ,ġ,ģ,г,γ',
                'h'            =>   'ĥ,ħ,Ħ,х',
                'i'            =>   'ì,í,î,ï,ı,ĩ,ī,ĭ,į,и,й,ъ,ы,ь,η,ή',
                'ij'   =>   'ij',
                'j'            =>   'ĵ',
                'ja'   =>   'я',
                'ju'   =>   'яю',
                'k'            =>   'ķ,ĸ,κ',
                'l'            =>   'ĺ,ļ,ľ,ŀ,ł,л,λ,ḷ',
                'lj'   =>   'љ',
                'm'            =>   'μ,ṁ',
                'n'            =>   'ñ,ņ,ň,ʼn,ŋ,н,ν,ṅ,ṇ',
                'nj'   =>   'њ',
                'o'            =>   'ö,ò,ó,ô,õ,ø,ō,ŏ,ő,ο,ό,ω,ώ',
                'oe'   =>   'œ,ö',
                'p'            =>   'п,π',
                'ph'   =>   'φ',
                'ps'   =>   'ψ',
                'r'            =>   'ŕ,ŗ,ř,р,ρ,σ,ς,ṟ',
                's'            =>   'ṣ,ş,ś,ŝ,ş,š,с',
                'ss'   =>   'ß,ſ',
                'sh'   =>   'ш',
                'shch' =>   'щ',
                't'            =>   'ţ,ť,ŧ,τ,ṭ',
                'th'   =>   'θ',
                'u'            =>   'ù,ú,û,ü,ũ,ū,ŭ,ů,ű,ų,у',
                'v'            =>   'в',
                'w'            =>   'ŵ',
                'x'            =>   'χ,ξ',
                'y'            =>   'ý,þ,ÿ,ŷ',
                'z'            =>   'ź,ż,ž,з,ж,ζ'
                );
 
                foreach( $glyph_array as $letter => $glyphs ) {
                        $glyphs = explode( ',', $glyphs );
                        $str = str_replace( $glyphs, $letter, $str );
                }
 
                return $str;
        }

Add field/field groups with titles of non-Latin characters.

Expected result

Field/field group aliases should be in transliterated form

Actual result

They are not

System information (as much as possible)

Joomla! 3.7.0-beta3 under Wampserver

Additional comments