Kaufmann...knew perfectly well that Nietzsche's actual target in the book is not Jesus and the values he is presented in the Gospels as espousing but rather the Christianity of St. Paul and his kindred spirits, and even though he also knew that, in German, the word "Christ" means "Christian" rather than (Jesus as) "the Christ" (which is "Christus" in German).The title, in other words, should have been The Anti-Christian. That's an interesting point, though I suspect Schacht overstates its significance for Enlish-language readers.
About the translations themselves, Schacht concurs with a point I've made here and elsewhere before, namley that while Kaufmann "had a good feeling for Nietzsche's style and a knack for capturing it" such that "in his translations, he makes Nietzsche come alive for the English-speaking reader, in a way that seems to me to be generally quite faithful to and reflective of the spirit and thrust of Nietzsche's own writing and thinking" (77-78), Kaufmann "also seems very frequently to have been motivated more by considerations of rhetorical effectiveness in English than by careful faithfulness to Nietzsche's texts" (78). That still seems to me a quite fair assessment.
More worrisome are the cases where Kaufmann "engag[es] in some tendentious shading and even some covert bowlderizing" (78). Schacht has three examples, not all equally convincing. With regard to BGE 36--the alleged "proof" of the doctrine of will to power (Schacht also makes hay out of translating "Lehre" as "doctrine" , though this seems to be much ado about nothing)--Schacht thinks Kaufmann tried "to soften its force" with some of his translation choices. Schacht is certainly right that the choices Kaufmann made are dubious or at least arguable, but it doesn't seem to me the meaning of the passage is affected, and that none of the translation points affect, for example, Clark's well-known argument that the argument in the passage can't be one Nietzsche actually accepts, since it depends on a premise he rejects. About GM III:12, Schacht makes the somewhat more interesting point that "auslegen" "literally means 'lay out' ('aus-legen')," and that the English "interpret" lends itself too readily to Nehamas-style misreadings. (He doesn't mention Nehamas, but he seems to be the target here.)
But the most striking example Schacht adduces (84) is BGE 230, in which Kaufmann rendered der schreckliche Grundtext homo natura" as simply "the eternal basic text of homo natura," omitting the adjective "terrible"! Schacht's explanation, which seems plausible, is that Kaufmann "no doubt was afraid that, if Nietzsche's English-speaking readers knew that he thought of this 'basic text' of our primordial 'natural' nature in that way, they would be too likely to suppose that he was endorsing the 'terribleness' and its unleashing" (84). Schacht, of course, agrees that would involve a misinterpretation of Nietzsche's meaning, but he's still right to complain that just dropping the word altogether (whose English meaning is quite clear) is really pretty bad translation practice. The question is how often Kaufmann does this. I can't think of a similarly dramatic case I've come across, but maybe readers can.