Well, I can now offer the answer to this question.
My return flight from Rome arrived in E, as expected. I quickly arrived at the Customs & Immigration area. But NOW, they've put a bunch of Global Entry kiosks there. They were yelling at people to check in there if you had Global Entry, so I did. But there were no signs re: transfer passengers this way, or Atlanta passengers that way. Don't know what happened to those. So I asked one of the yelling women: "I have no checked bags. Can I just go through immigration here so I can avoid the international shuttle? I don't mind going through security again." The answer: "NO! Atlanta passengers this way!!" I pressed somewhat, and she continued to insist that they would not let me through. Do they check boarding passes or something?
So I head the direction she says in order to start The Long March. Except--there are no signs where she told me to go, and in fact, there were stanchions set up BLOCKING the passage. I went back and asked. She bellows, "Just go over there! There's someone standing there and she'll let you through?" Oh, really? I had her escort me over and show me exactly what she meant. This is a new thing--I've never had to do this before, and it was really confusing for everyone. The Global Entry people literally have to backtrack to get to this small, blocked-off passage.
So international arrivals at ATL will continue to be even more of a cluster-f*** than they used to be. Hard to believe that's even possible, but it is.