"Alien" often just means "foreign" anyway. https://en.wiktionary.org/wiki/alien#Adjective

In what sense this a mistranslation? If you conflate alien with extra-terrestrial?

In current usage, people almost exclusively use "alien" to refer to ETs. The only ones who use it in the sense of "foreigner" are immigration bureaus, and this becomes a source of hilarity whenever they speak to the outside world.

Would you ever say "I had some aliens in my home last night for dinner" and expect someone to interpret that to mean immigrants/tourists/strangers? At best, they would criticize you for using that term to refer to them.

Illegal Alien gets quite a few hits on google.

https://www.google.com/#q=illegal+alien

Perhaps I should have said "immigration law enforcement" instead, but the same point. Outside the that context, "alien" means ET.

It isn't a literal mistranslation, it's a context error. In english the proper word in this context would be stranger, not alien. But that's still a mistranslation. Had this been something to do with immigration or visas, then alien might have been appropriate.

Merriam Webster's definition 1A for "alien" is belonging or relating to another person, place, or thing : strange. I think it fits the context very well.

http://www.merriam-webster.com/dictionary/alien

But if you take Webster’s definition, alien is still overbroad. A person OR place OR thing is a much wider scope. 'Stranger' only describes persons and so is still the appropriate word in the context.

> But if you take Webster’s definition, alien is still overbroad.

That it could perhaps encompass other meanings than the intended one does not make it incorrect for the intended meaning.

> 'Stranger' only describes persons and so is still the appropriate word in the context.

"Stranger's" would be more specific than "alien", and wouldn't be a bad translation, but "alien" is likewise not a bad translation (and, actually, has almost exactly the same breadth in English as "étrangère" does in French; so its arguably the most exact translation, since it uses a word that both admits the specific sense intended within its scope and which has a pretty similar breadth of association as the source.)

Its also the idiomatic word in English for describing something which provokes a feeling of distance from the speaker in a way which is quite appropriate for the subject matter, so its probably the best translation idiomatically.

Overbroad? "Étranger", in French, is just as broad as "alien". It can be used for people, places, things, and more. Save for the ET meaning, any use of "alien" or "foreign" can be translated to "étranger", and vice versa. It is a very broad word.