Berlin Landesarchiv collected the new family records
Why did the Wohlgemuth-Katz records recently become available? For two wonderful reasons.
First, a 2009 amendment to civil status law designated the Berlin Landesarchiv as the agency to centralize disparate historical records and make them available to the public. Second, a Landesarchiv project begun in 2014 to put many records online via a partnership with the German office of Ancestry.com.
So all the info I found yesterday was made available on Ancestry beginning sometime in 2015. The same information is also available on a German genealogy site, probably also recently published.
The Landesarchiv has reading rooms open to the public at their building in a former munitions factory in Borsigwalde in North Berlin near the Eichborndamm S-Bahn stop. This is also the place where the German liquidated-business database project was conducted. I don't think there is any reason for Jo to go there on her last day. Probably I would spend time in these archives if I visit next year.