Your code contains an error. Even if it compiled, it would not search for what you want. The qr'red strings are interpolated as (?-xism:$string). So you would actually search for e.g. /\btak[(?-xism:ABVH)]/, what i'm sure is not what you want.

Consider the following code (i can give an example in Cyrillic-Windows-1251, but i don't know if it's compatible with Belorussian variant): 

my $letters = '[a-zA-Z]'; # try - maybe the character range will work 
+for you. It works in Cyr-1521, but does not in KOI8-R
my @wordpatterns = map { qr/(?<!$letters)(\Q$_\E$letters*)/ } qw(tak h
+et hen toj);

while (my $next_line = <$FH>) {
    foreach my $pattern (@wordpatterns) {
        my $count_words = ($next_line =~ s/$pattern/>$1</gi);
    }
}

[download]
The code is untested, but must do the Right Thing in much better way than yours. It re-uses the generated regexes and may make processing of large amounts of data noticeably faster.

One more note—the /i switch won't work for Cyrillic encodings without carefully set locale. The behaviur of boundaries (\b) is wrong, if the locale is wrong—so i removed them from my regex too.

     s;;Just-me-not-h-Ni-m-P-Ni-lm-I-ar-O-Ni;;tr?IerONim-?HAcker ?d;print

In reply to Re: variables in regex character classes by Ieronim
in thread variables in regex character classes by amir_e_a

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