"You cry until you laugh."
Translation:Man gråter inntil man ler.
Until is actually a Norse word, it is made from two elements 'un' (up to ) + 'til' (to).
'Til' was originally a noun meaning goal or endpoint that became idiomatic as a preposition in North Germanic languages).
'Un' comes from Proto-Germanic 'unþ', in Old English this is 'oþ' (used also in phrases like 'oþþæt' (until that/which)), but Norse languages kept the -n- and lost the -þ (compare Tooth and Norwegian Tann, both from Proto-Germanic 'tanþs', or Mouth with Norwegian Munn, from Proto-Germanic 'munþaz'). Thus English has favoured the Norse form instead.
I was hoping to see an answer to your question, but no luck so far. In the part of the Duo course that I've covered, én seems to be restricted to the number 1, and not used as a pronoun. But I'll go out on an (uninformed) limb and suggest that it wouldn't be wrong to use it as a pronoun, if you wanted to put emphasis on that word.