It really isn't a terrible piece of film. The acting is good, the story is engaging and the cinematography is excellent. Film quality is good as well, the reel was in good shape when this was digitized.
It's certainly not any more 'antisemitic' than the film 'house of rothschild' which was presented to American audiences as a philosemetic film.
were to guess why no t4 personnel were chosen to perform gassing that had experience with gassing, it would be because THERE WERE NONE.