I still don't see the point, but here's a simpler and more canonical way. It shows how to do it for both an encoded and decoded string.

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

use Text::Unaccent::PurePerl qw(unac_string);
use Encode qw(encode);

binmode *STDOUT, 'encoding(UTF-8)';

my $string = "c\N{LATIN SMALL LETTER O WITH CIRCUMFLEX}te";
my $rstring = encode('UTF-8', $string);

print "$string $rstring\n";
my $direct = unac_string($string);
my $via_bytes = unac_string('UTF-8', $rstring);
print "$direct $via_bytes\n";  # cote cote
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