My previous solution works in every other page, but stopped working with ContactController.php on presta 1.6.1.18. It works if I add
'cms' => CMS::getCMSContent('7', $this->context->language->id)
directly in /controllers/front/ContactController.php. It looks like overriding of this controller is impossible now. Can anyone confirm or have a fix for this?
E: The solution is to force compilation and clear cache once