Yes, but why "venimus"? Is it only idiomatic? I really don't understand why Latin uses "venir" if the conversation is just started, and not already going on.
Edit: I've found in the Gaffiot another meaning, and it's the only meaning they give:
In colloquium venire = roughly translated from French by "to go to an inteview" (not a job interview, but only a chat between two persons or more (se rendre à une entrevue).
For me, it explains completely the reason of the presence of"venire", that I would find illogical without that.
It gave the word "colloque".
I understand, but I'm still searching, and I can find only the "interview" meaning (i.e "colloque"). Olivetti gives the same. It gives only colloque/entretien/entrevue (sadly they give the translation only in the French and Italian site, not the English one)
Colloque is the French word for seminar (séminaire).
Italian for colloquium: conversazione, dialogo, incontro
French for colloquium: conversation, dialogue, rencontre.
So, even if we can't ask native people here, I really think it makes sense, and it's a better translation than the meaning suggested here. When it's venire, they don't translate it by conversation, but seminar.
There is an infrequent English expression that may be an equivalent, and is perhaps a little old fashioned now. "I fell into conversation with a centurion yesterday". This idiom probably implies "by chance, with someone I had not met previously". There is another idiom, though, which may be closer to our meaning: "I got into conversation with the boss yesterday, and she was very encouraging about our proposals". English has two idiomatic ways to cover this Latin situation.
See my reply to PERCE_NEIGE elsewhere in the discussion. I would not use this idiom to describe a simple conversation. There is a verb colloquor meaning to talk together, converse, hold a conversation, a parley, or a conference. So "we are in conversation" - colloquimur. There's also an anteclassical verb: confabulor giving confabulamur for "we are in conversation".
Having read and, I hope, understood the comments in this discussion to date (12th November 2019), I'm still not clear whether there is agreement that "We have a conversation" is, or is not, a reasonable translation of "Nos in colloquium venimus". On the face of it, fairly literal translations, "We come into the conversation" or "We come into conversation", as others have suggested, emphasise the commencement of a conversation or that the speakers are joining an existing conversation,. That's not quite the same thing as simply "We have a conversation".
There appear to be classical references involving colloquium or colloquia that use habere or other verbs; I found examples at https://translate.enacademic.com/colloquium/xx/xx/. So I question whether venimus is the best verb to choose for a sentence "We have a conversation".
EDIT: A year after I wrote the above, the link I provided unfortunately seems no longer to be accessible.
Gaffiot, Lewis, Olivetti, Dicolatin, all say that it's not a good translation.
Even if "conversation" is one of the meaning for "colloquium", it's not the first one, but, more importantly, the crucial thing is not to translate "colloquium" alone, but the whole expression "colloquium venire", and to know what would be "ad colloquium venire", to compare.
Because when expressions do exist, it's absurd to translate "venire" alone, and "colloquium" alone, and to concatenate the 2 meanings.
We have examples of these translations, for instance, in "Entick's New Latin-English Dictionary: Containing all the words and phrases proper for reading in both languages", they translate:
To parley = In colloquium venire.
Other dictionaries or translated texts give the same thing. Never the Duo's version.
I think the contributors have misused the idiom here. I can't find examples of in colloquium venire with the bland meaning of "have a conversation". It seems to be more to do with engaging formally in a conference or parley.
E.g. in Caesar's De Bello Gallico 1, 35: in conloquium venire invitatus - "invited to a conference". And 1, 43: ut erat dictum, ad conloquium venerunt - "as had been appointed, they came for the conference".
Then from the early modern period we have from Francis Bacon's History of Henry VII: Ille fuit ut rex Scotiae cum rege Henrico apud Novum Castrum congredi et in colloquium venire vellet. - "Which was that the King of Scotland wished to meet with King Henry at Newcastle and parley."
Not just for an idle chat, surely.
There are so many ways of translating this including: we are conversing; we are in conversation; we are talking (to one another); we are having a talk (chat)... that I suppose it is impossible for Duolingo to take account of them all, but one or two options other than the single one that is on offer would be nice.
I am not an expert, but in this sentence, I think that the key is the accusative form (in colloquium), which means direction or intention. The use of the verb "venimus" also suggests this meaning: " We come to talk". It is just my opinion, but I always want to help: "in auxilium venio" (I come to help, the same structure, by chance).