I don't comment on the Kanzlerakte, it's obvious fake.
US barracks are not extraterritoriality zones, please cite your claim.
"US soldiers are not under German jurisdiction", this is only partly true. It's part of the "NATO-Truppenstatut". With Art. 19 Abs. 3 Satz 1 ZA (Zusatzabkommen) the foreign soldiers are part of German jurisdiction.
US barracks are extraterritoriality zones, and US soldiers are not under German jurisdiction.
And better read the 2+4 itself, and not 3rd party writeups like Wikipedia.