Also, I used XML::LibXML to parse the structure.

#!/usr/bin/perl
use warnings;
use strict;
use utf8;

use XML::LibXML;

my $file = shift;

my %to_cyrilic = (
    # Insert the hash definition here, see below.
);
my $regex = join '|', sort { length $b <=> length $a } keys %to_cyrili
+c;

my $dom = 'XML::LibXML'->load_html( location => $file );
for my $text ($dom->findnodes('//text()')) {
    my $etext = $text;
    $text->setData($etext) if $etext =~ s/($regex)/$to_cyrilic{$1}/g;
}
print $dom;
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Note that PRE tags preserve non-latin1 characters.

    F => 'Ф',
    H => 'Х',
    N => ':',
    Nj => 'Њ',
    b => 'б',
    c => 'ц',
    d => 'д',
    e => 'e',
    h => 'х',
    i => 'и',
    l => 'л',
    m => 'м',
    n => 'н',
    nj => 'њ',
    p => 'п',
    r => 'р',
    s => 'с',
    t => 'т',
    u => 'у',
    v => 'в',
    z => 'з',
    ć => 'ћ',
    Č => 'Ч',
    č => 'ч',
    Đ => 'Ђ',
    đ => 'ђ',
    Š => 'Ш',
    š => 'ш',
    Ž => 'Ж',
    ž => 'ж',
    # etc., this is enough to run the example.

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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