Compare a list of locales with the actual xml file on facebook to check for new additions.

FB locales compare

<?php
// This list is not actual, because it's shortened
$fb_valid_fb_locales = array(
	'ca_ES',
	'cs_CZ',
	'cy_GB',
	'da_DK',
	'de_DE',
	'eu_ES',
	'en_PI',
	'en_UD',
	'ck_US',
);

function facebook_locale_compare($fb_valid_fb_locales) {

	$xml = simplexml_load_file( 'https://www.facebook.com/translations/FacebookLocales.xml' );
	
	foreach ( $xml->locale AS $locale ) {
		if ( ! in_array( $locale->codes->code->standard->representation, $fb_valid_fb_locales ) ) {
			$new_fb_locales[] = (string) $locale->codes->code->standard->representation;
		}
	}

	if ( ! empty( $new_fb_locales ) ) {
		$fb_valid_fb_locales = array_merge( $fb_valid_fb_locales, $new_fb_locales );

		echo "<h1>There are some differences!</h1>";
		echo "<p>Number of additions: ".count($new_fb_locales)."</p>";
		echo "<h2>New array to copy:</h2>";
		echo "<code>";

		echo '$fb_valid_fb_locales = array(<br />';
		foreach ( $fb_valid_fb_locales as $locale ) {
			echo "&nbsp;&nbsp;&nbsp;&nbsp;'{$locale}',<br />";
		}

		echo ');';
		echo "</code>";
	}

}