Interesting! One thing, though: Steve Zaloga makes notice of this gun in the (strangely named, IMHO) "German Panzers 1914-18" Osprey book, as the proposed armament for the A7V tank. He states, however, that it was discounted as early as 1917 due to its insufficient performance against both AFVs, emplacements and soft targets, and ultimately replaced in the design by the combination of a 57mm gun and six MG08 HMGs.
So some discrepancies, and I would certainly like to see some period sources on that... Zaloga doesn't give a proper reference for his statement either, though.