Locale not working

I am using Polylang and I was thinking to dinamically set locale.

$lang_locale = pll_current_language(‘slug’);
switch($lang_locale ){
case ‘en’ :
$lang_locale = ‘en_US’;
case ‘de’ :
$lang_locale = ‘de_DE’;
}
echo do_shortcode(‘[sfp-page-plugin width=320 show_facepile=false locale=”$lang_locale” url=asdfsdf]’);

The locale variable this way is set just fine, it is just the same as on https://www.facebook.com/translations/FacebookLocales.xml but the end result is always in english.
If this works, I’ll rate with 5 stars ??

https://www.ads-software.com/plugins/simple-facebook-plugin/