"Ora fa benissimo il suo nuovo lavoro."
"Now he is doing his new work very well" should also be accepted as a valid translation for this sentence.
I have the same question. I put "Now his new work goes very well." Specifically, it seems to me like the subject of "fa" could be either "lui" or "lavoro."
"Now he is doing his new work very well" should be accepted as a valid translation along with "Now he does his new work very well."
Because that's grammatically incorrect in English. You could say "Now he does very well AT his new job".