How do you translate the question "which other languages do you speak?"

Take care with adjective endings. Quel is masculine singular. Langue is feminine, and here it's plural, too. That's quelles.

My original question included the word "do" [...] but this might be just an artifact of the english language

Ouais, évidemment. You can't translate things 1:1...

Regarding my second translation, I'm actually not sure if you can use the ubiquitous « est-ce que » phrase here.

...but some rules apply between both languages. Does it work in English?

Which other languages is it that you speak?

Nope. If you forced it into this construction, you'd have to change some things around:

Which other languages are they that you speak?

But for the record, neither of these is something you'd say in French (or English). So we arrive at:

Quelles autres langues parlez-vous ? ou Quelles autres langues parles-tu ?

/r/French Thread