Some basic reading should set your "engineer" friend straight. Of course, that might be asking too much
I routinely have to tell engineers what they screwed up. Stuff they are
supposed to know. And I only have a high school diploma. The ability to pass classes and a test rarely translate to competency in the real world in my experience. Also, in Texas there is no subcategory. You get licensed as a professional engineer and you can practice structural or civil or mechanical engineering. No additional training needed.