use strict;
use warnings;
use XML::Twig;

my $infile = "in-test.xml";
my $outfile = "out-test.xml";

open(OUT, ">$outfile") or die "can\'t open output file $outfile:$!";
open(IN,  "$infile")   or die "can\'t open input file $infile:$!";

my $t = XML::Twig->new
    (
    twig_roots => {'figure' => \&doSwap},
    twig_print_outside_roots => \*OUT,
    );
$t->parse (\*IN);

close OUT or die "Could not close $outfile";
close IN or  die "Could not close $infile";

sub doSwap {
    my ($t, $figure) = @_;                          # required arguments for twig handlers
    my @title = $figure->cut_children ('title');    # extract (the only) <title> node from the <figure> node
    $title[0]->paste (last_child => $figure);       # make it the last child of that <figure> node
    $figure->print(\*OUT);                          # print the rearranged <figure> node
}