An old subject, but an interesting one in this application. I believe that all states have legal constraints on the use of the terms "Engineer" and "engineering" when it comes to building and systems design and construction, especially anything that potentially has to do with the health,
safety and welfare of the general public. And the usage has nothing to do directly with a degree, it has to do with being a licensed and registered Professional Engineer (PE) in the related discipline, which is done on a state-by-state basis. Calling yourself an Engineer or offering engineering services in such applications not only opens you up to legal charges of practicing without a license, it also implies a degree of liability that you would probably prefer to avoid.
However, some states do allow the use of the term Engineer in relation to building and systems operations, here in Georgia the law specifically provides just such an exemption for systems and facility operators. While you definitely need to verify the specific laws for the state you are in, as an operator you may be able use the title Engineer but if you provide any services related to the design or construction of a
theatre or the tech systems, then you would probably not want to use that title.
What is ironic in this is that with an Engineering degree, a PE and Professional Liability insurance, I actually avoid using the terms "Engineer" and "engineering", especially in relation to any building or systems design or construction, as I recognize the implications in doing so.