Meta keywords and description on page localized

Yes.
I did it with 3 user-defined fields in the backend:
meta-decription-de
meta-decription-en
meta-decription-fr

then, in the HTML template, you need to check the language and select the appropriate meta-field:

//	$language = $_GET['lang']; // if using query mode
//	$language = $q_config["language"]; // if using folder mode

		$field = 'meta-description-'.$language;

		// get data for META-Tag 'description' from DB
		$metadaten = get_post_meta($post->ID, $field, true);

		// if found anything, use it; if not, use default text
		if ("" == $metadaten) {
			switch ($language) {
				case 'de':
					$metadaten = "my german default";
					break;

				case 'en':
				$metadaten = "my english default";
					break;

				case 'fr':
				$metadaten = "my french default";
					break;

				default:
				$metadaten = "my default default";
					break;
			} // end switch
		} // end if

		echo "<meta name='description' content='$metadaten'>";