when having multiple instances on one page, is it possible to switch the directionality per instance

E.G.:

public function getCMSFields() {
	$f = parent::getCMSFields();
	foreach($this->getTranslationFields() as $field) {		    
		$title = $field->Title();
		// last 5 characters are respresenting the locale 
		// en_GB, de_DE, ar_SA
		$locale = substr($title, strlen($title)-5));
		if( $field instanceof HtmlEditorField && $locale == 'ar_SA' ) {
			// what to do here, to switch the directionality?????
		}
		$f->addFieldToTab("Root.Translations", $field);
	}
	return $f;
}

Any ideas would be great !