Question: are Boulevard Solitude and Moses und Aron both German librettos?
Sentence (from "Moses und Aron"): Hungarian composer Zoltán Kocsis completed the last act, with Schoenberg's heirs' permission, in 2010, but as of 2014 "Moses und Aron" was almost always performed as Schoenberg left it in 1932, with only two of the planned three acts completed.
Relevant evidence: No