World of Tanks has repeatedly had military personnel updating the technical specifications with details they have found in the secret manuals.
Those documents are often secret or top secret, or even more compartmentalized.
There are training docs in wide use today that are not publicly findable on the internet, nor are they seemingly in the datasets of LLMs.
I'm sure there are reasons for that, of course.
What you're talking about would have an even higher level of obscurity and secrecy, and probably Compartmented Information access.