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

my $twig = XML::Twig->new(
	char_handler => sub {
		my ($txt) = @_;
		$txt =~ s/"(.*?)"/'$1'/g;
		return $txt;
	},
	### Note: These are included for terminal ease.
	### The problem still exists without them.
	pretty_print => 'indented',
	keep_encoding => 1,
);
$twig->parsestring(*DATA);
$twig->flush();

__DATA__
<root>
	<data>"A", "B&#x2014;C", "D"</data>
</root>

##</code><code>##

<root>
  <data>'A', "B&#x2014;C', 'D"</data>
</root>

##</code><code>##

<root>
  <data>'A', 'B&#x2014;C', 'D'</data>
</root>