This is wrong:

    my $xml = do {
        local $/ = undef;
        open (my $fh, "<:encoding(ISO-8859-1)", $file) or die "Failed 
+to open $file - $!";
        <$fh>;
    };
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It should be:

    my $xml = do {
        local $/ = undef;
        open (my $fh, "<:raw", $file) or die "Failed to open $file - $
+!";
        <$fh>;
    };
[download]

XML files are binary files (parsing the document is required to determine the encoding), not text files (files where the encoding is external to the document). It is the parser's job to handle decoding.