In "Rhapsody in Blue" why didn't Zhaan get the coordinates for Delvia from the Delvians they encountered on the planet? It seems strange she was willing to have Pilot's arm severed just episodes earlier to get them, but then she runs into her own race and asks nothing?
Those Delvian's even had plans to return to Delvia and lead a revolution, so obviously they know where it was.
In the first season, Episode 9 "DNA Mad Scientist". It can be misunderstood what the crew is precisely doing, what getting their eye fluid extracted in order to obtain maps.
They are indeed looking for a way to get home. It is not simply to know where home is. It is to obtain a path/route that will allow them to bypass any and all Peacekeeper territory, outpost, colonies, etc. They want this because every single one of them is wanted by the pesky Peacekeepers.
So in answer to your question, yes, Zhaan could have asked "where" the Delvian home world was. Problem would have been in "how" she was to safely make her way there.
Hope that helps!