Don't just replace :utf8 with :encoding(iso-latin-1).

Instead of

my $qfn = $CFG->{admin_root_path}."/amazon_template_tmp/it_other.csv";

open(my $fh, '>:encoding(iso-latin-1)', $qfn)
   or die("Can't create \"$qfn\": $!\n");

print($fh $the_contents);
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use Encode qw( encode );

my $qfn = $CFG->{admin_root_path}."/amazon_template_tmp/it_other.csv";

open(my $fh, '>:raw', $qfn)
   or die("Can't create \"$qfn\": $!\n");

print($fh encode('iso-latin-1', $the_contents, Encode::FB_HTMLCREF));
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That way, characters that can't be encoded using iso-latin-1 will be replaced with HTML escapes (e.g. ♠ ⇒ ♠).