I have also verified that reading the XML file and writing it out again like so:
Probably string downgrading issue again. Try to 
binmode STDOUT, ':encoding(utf-8)';

[download]
put that on top of your program.

If that doesn't work, post the output of

my $xp = XML::XPath->new(xml => $xml)
    or die "ERROR: XML::XPath cannot parse target file: $!\n";

my $contrib_nodeset =
    $xp->find('/contrib[@contrib-type="author"]');
foreach my $contrib_node ($contrib_nodeset->get_nodelist) {
    my $given_names = $xp->find('./name/given-names', $contrib_node);
    my $surname     = $xp->find('./name/surname',     $contrib_node);

    printf "given_names => (%d) %vx\nsurname => (%d) %vx\n",
      utf8::is_utf8($given_names), $given_names,
      utf8::is_utf8($surname),     $surname;
}

[download]
(with problematic strings)

In reply to Re: XML::XPath and character encoding by Anonymous Monk
in thread XML::XPath and character encoding by mboudreau

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