Abe Ratner was from Minsk
In the 1920 census form for the Ratner family, the enumerator first wrote down Minsk and then crossed it out and wrote Russia for Abe's birthplace. Similarly, Rose is noted as born in Rostof, which is also crossed out and replaced.
To see what I mean, click on the image to display it fully, then click again to zoom in. The first family at the top are the Ratners Abe himself is on the previous page but the others are here. Look under father's and mother's birthplace to see the cross-outs.
So then I did a quick look for the name Bloch in the JewishGen Belarus database. What pops up are lots of people named Blokh in the Minsk guberniya. On a first pass, I didn't find a Abram Blokh born in May 1869, but I think it is pretty likely we now have the original home region for another of our eight great-grandparents.
To recap:
• Selma Ratner's parents came from Rostov by way of Rezshita in Latvia (Rose) and the Minsk area of Belarus (Abe).
• Walter Rabinowitz's parents came from Lithuania probably Kovno (Joseph) and unknown but probably also Kovno guberniya)
• Hermann Ringel's parents came from the Rzezow area of Poland (Schija) and Krakow (Feigel).
• Elly Wohlgemuth's parents Julius and Bette resided in Koenigsberg but we don't yet know where they were born.