I don't think you can use Vale within the php class/method - this text seems to be missing:

Probs need to use it before the method declaration?

I checked my changes, and it's the same with the live website. So they all actually broken.
Maybe let's just remove the vale here. Might give some errors, but it's because of the code

This is weird. I removed the vale statements completely from here, but the result is still the same as your screenshot.

I'm not familiar with php.
But can you confirm that the whole block is php code block?

.. php:class:: Mautic\CoreBundle\Event\RouteEvent

  .. php:method:: getType()

      :returns: The :ref:`route firewall<plugins/config:Routing firewalls>` for the given route collection.
      :returntype: string

  .. php:method:: getCollection()

      :returns: Returns a RouteCollection object that can be used to manually define custom routes.
      :returntype: \\Symfony\\Component\\Routing\\RouteCollection

  .. php:method:: addRoutes(string $path)

      Load custom routes through a resource file such as yaml or XML.

      :param string $path: Path to the resource file. For example, ``@FMElfinderBundle/Resources/config/routing.yaml``.
      :returntype: void

If so, I think I know where it's gone wrong.

I've removed the vale off/on. I'm not sure how these RST syntax should be rendered on the site, though. I'm asking confirmation from Rahul on Slack.

The "rendering problem" has been fixed in #269. 👍🏼