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The magic word {{CONTENTLANGUAGE}} doesn't show the selected language, and therefore it cannot be used to create templates that will display text according to the language selected.

I've created a new magic word as part of my copy of UniversalLanguageSelector that may be of use to others, or even included in further releases: {{CURRENTUNILANGUAGE}}

New UniversalLanguageSelector.i18n.magic.php file:
$magicWords = array();
$magicWords['en'] = array('currentunilanguage' => array(0, 'CURRENTUNILANGUAGE'));

Added to UniversalLanguageSelector.php, below last hook:
$wgHooks['ParserGetVariableValueSwitch'][] = 'UniversalLanguageSelectorHooks::getLanguageMagic';
$wgHooks['MagicWordwgVariableIDs'][] = 'UniversalLanguageSelectorHooks::getLanguageMagicDeclareVarIds';

Added to UniversalLanguageSelector.hooks.php, above getLanguage(...):
public static function getLanguageMagicDeclareVarIds( &$customVariableIds ) {
    $customVariableIds[] = 'currentunilanguage';
    return true;
  }
public static function getLanguageMagic(&$parser, &$cache, &$magicWordId, &$ret ) {
    if ( 'currentunilanguage' == $magicWordId ) {
      $context = RequestContext::getMain();
      $code = $context->getLanguage()->getCode();
      $ret = self::getLanguage($context->getUser(), $code) ? $code : '';
    }
    return true;
  } 


Works like charm :-)