WordPress Developer for Existing Build

Hello. We need a WordPress developer who will help us make sense of an existing build and most importantly, who is able to explain the setup to us and provide insights into how it works. To give you a clue - the previous developer used Advanced Custom Fields from WP Engine. There are a lot of pages that are "missing" from the menu, yet they exist on the website. I'm confused and I need someone to properly explain why it is that way, how to find pages to edit, or is it possible to make it more straightforward. I've only used themes on WP, where editing pages is pretty straightforward. Looking for a knowledgeable person who is a great communicator. This is primarily a consulting and auditing phase to help us understand our current setup. If we work well together, this can turn into a long-term role for ongoing updates and maintenance.