"No one knows the traveler who is waiting over there."
Translation:Personne ne connaît le voyageur qui attend là-bas.
This is something a bit odd. Apparently a minor SW bug in DL or the database:
My answer as typed cut and pasted and accepted: Personne ne connait le voyageur qui attend là-bas
DL's suggestion "Another correct solution:" Personne ne connaît le voyageur qui attend là-bas.
Other than the period, I notice that I missed the circumflex in connaît.
Is connait really an acceptable alternate word?
Yes, the 1990 spelling reform proposed connaitre for the infinitive and connait for the third person singular present.
The version without the circumflex doesn't seem to have gained much of a footing in standard usage (so it's reasonable for Duolingo not to have chosen it as the primary version taught), but it makes sense to include it as an alternative in the database.