Translation:In front of which station are we supposed to wait?
This wouldn't be used in spoken English. "Which station are we supposed to wait in front of?" is the normal formulation; preposition-final questions are a key feature of spoken English.
"Máme" in past sentences has been translated as "are to". Therefore, "In front of which station are we to wait?" should be accepted.
I said, "In front of which station do we have to wait" and it was rejected. Why?