I like this line of thinking. I see a project engineer as an actor within the system. They should be working to achieve the goals of the project lead or executive, whether that is themselves or another actor in the system. They may be executing the tasks themselves or working in collaboration with other actors (subcontractors, vendors, clients, etc.) to navigate obstacles, complete tasks, and keep the project on track and on budget. To me, systems design is more meta than project management. Thinking about what market a business is operating in. Working on the culture of an organization. Project managers work within the system, and influence its structure by acting within it (recommending different contractors, calling out high performers and underperformers, reporting on progress, etc.) but their primary role is not to focus on the system itself. It's to deliver an outcome within the constraints of the system.