The key questions I saw were that you had to dig to find these isues, many electrical upgrades use the old original rires in the walls and attic also many states say home owners the occupy there home do not need permits to do repairs fdor their own homes only if a outside company is doing the work.
The sellers disclosure is to their knowledge so depending on how long they owned the home they may have never had a need to go into the attic to ever find what you have meaning that may have been their prior to them owning this home and simply have no knowledge of it
Good Luck and I would assume with the shocking issues the home inspector should have noticed something wrong with his tester for outlets I would ask what he noted thru out the home too
Good Luck, Terry Bell, Realtor, Santa Rosa, CA
I am really sorry for your situation, but suggest you look into it. Hopefully something will work out for you.