I am at a loss as to what you are trying to accomplish and with what. I understand the words, but not their meaning...
You have "upgraded your single entity CMS to a centralised core"... I don't know what that means to your code.
"Deploy page permissions in our ACL"... Is that a Policy that determines whether the user can access a specific page?
"Individual pages need to somehow render within the permissions page"... I don't know where the rendering comes into play and why they need to render within the permissions page (what IS the permissions page in this context?) just because they have a key
"I know that events shouldn't really be used in this way"... I don't know what "this way" means to you. Usually when using events in Laravel, you would create individual listeners for the actions you want to perform when a certain event happens. A "page.pages.OnGet" event is really not very descriptive - unless it means "A page was served" in which case I would argue that this is Controller logic? Reacting to the incoming request (be it GET or POST) is Controller domain...
Where in the code are these events triggered?
very confused about pretty much every sentence in your post :)