GA 50 also contains Heidegger's undelivered lecture from 1940, Nietzsche's Metaphysics, which has already been published in English and is not translated here.I tried to find that, but the only English Nietzsche's Metaphysics I could find is Frank A. Capuzzi's translation in volume III of the English Nietzsche, and that one is from GA 6. Krell says in his editor's preface:
"Nietzsche's Metaphysics"...is not (as was once believed) a lecture course from winter semester of 1941-42 but a sixty-four page typescript dated August 1940.So, where was Nietzsche's Metaphysics from GA 50 translated? The new book goes so far as to include supplements for Nietzsche's Metaphysics.