Tracking a person actually seems pretty easy to do. Hack their phone, launch ze missiles. Obviously not trivial, but it is pretty easy to imagine a chain of events involving a little social engineering and a little spycraft involving the major tech companies. The Iranians thought they were mid-negotiations and assassinating their leadership seems counterproductive even in hindsight, I doubt they were using heightened opsec.

Getting the layout of an underground facility, on the other hand, is quite hard to do even on purpose. They'd really want the engineering plans I suppose - which should be quite secure even on a bad day. I wouldn't assume it was secure but it'd be harder than finding senior leadership who often go out in public or to their kids school plays in a regular year.