Hi Razvan,
I'm not sure why this happens, but it could be because of the mechanism that those pages are only rendered in case the application is down.
Wouldn't it be a much more simpler solution to point the user to a similar page that is configured in the modeler? You can then use a datasource somewhere on your page that checks the maintenance boolean. If the boolean = true, you can redirect the user to the page you configured in your modeler.