Dumb translation of the prophecy in french [spoiler)

I just watched this movie last night and was confused a good part of the story because of the translation of the prophecy.

They tranlated it by, roughly, "7 sons will leave, 6 [of them] will return", because in french the plural is associated with 6 and is shown in the verb.
In french it was, "7 fils partiront, 6 reviendront".
Then this prophecy is very clear in this translation and isn't at all mysterious.
So, I thought the mother was sad and anxious because she knew one of her son will die, but which one ? Suspense...

But when the first brother died, then the 2nd, and we are just in the middle of the story, I understood they will all die except one, but then the prophecy seemed completely wrong. I expected some explanation at the end, but finally there was nothing and I was left doubful.

Then I came here to find something and wrote the sentence in english "7 sons will leave, 6 will return", and then by reading it I suddenly understood the whole thing, because it makes sense in english.
So I had to translate a cantonese sentence translated in french from french to english to understand it. Crazy!
It made me want to work on the translator's teeth with a drill, or something like that...

This story of 7 brothers made me think of another movie I had, "The 8 Diagram Pole Fighter" (1984).
In this one they translated the prophecy in french "7 quittant, 6 revenant" ("7 leaving, 6 returning"), which is far more mysterious and far more accurate, because here the plural isn't shown.

Did someone experienced another dumb translation of the prophety in his language ?