After her murder in Vegas, Chantal tells Hutch: "One down, one to go". Italian editors of Sky Atlantic have translated it: "Uno al volo, uno no". This has a precise meaning in Italian: it means that Duncan Todd has been killed with one shot, while Roger has required two shots. Since translators know what's behind every dialogue, I wonder whether it was just an erroneous or ambiguous translation or means that Chantal and Hutch are really not interested in Cooper/the Jones and went to Vegas just to get rid of Duncan Todd and his assistant.
It literally means, out of the two people they were told to kill, one has been killed, leaving one more to do.
Yes, the translation can't fit, "one to go" can only refer to the future.
it means that Duncan Todd has been killed with one shot, while Roger has required two shots.
That is an odd choice for a translation, indeed. I agree with your interpretation of it, but they must have misunderstood Chantal's line, I don't know how you get from "one down, one to go", to that. Uno al volo is not even an idiom, is it? Sometimes I don't know what they're thinking, or how.
Anyway, from Part 16 Chantal and Hutch didn't even have the chance of looking at the Jones, so the weird translation choice does not hurt so much. Even if it may spoil to who is looking at Part 15 they will never accomplish the task that was contained in the English-language dialogue.
Fire walk with