Just use XPath to find the child element and its attribute:

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

use XML::LibXML;

my $parser = 'XML::LibXML'->new();
my $doc    = $parser->parse_file('file.xml');

for my $title ($doc->findnodes('//gotoButton')) {
    my $button  = $title->getAttribute('name');
    my $display = $title->getAttribute('display');
    my $caption = $title->findvalue('caption/@caption');
    print "$button\t$display: $caption\n";
}
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