I don't know why you would jump straight to the building department in this case.

I would contact different licensed electricians in your area, explain the situation, and see if any would be willing to inspect it for you and determine what would need to be updated. You'll end up paying them for it but they aren't going to turn you in if they get out there and it's a complete wreck. You're also probably going to have to call around, since many companies are not going to want to put time and effort into checking stuff they didn't do.

Would just share a personal experience that we hired a licensed general contractor to do work but they did not get any of the required permits for the work they did. After a few calls we were able to find an electrician that was willing to come out, inspect the work they had done, replace the work that needed to be replaced, and procure a permit on our behalf. So it happens.