I know you’ve been waiting for the definitive assessment of what Carnap was up to in his unpublished Untersuchungen zur Allgemeinen Axiomatik from the late 1920s.  Georg Schiemer, Erich Reck, and I wrote a paper about it.  I’ll leave it to you to judge whether this paper is the definitive assessment you’ve been waiting for.  It’s forthcoming in a Synthese special issue on Carnap on Logic, collecting contributions from the wonderful Munich conference of the same title organized by Georg. (If it’s paywalled for you, here’s a preprint.)