I asked this in a different thread about the same sentence and I'm not sure I really came away with a straight answer. Fhathast seems mostly to be used to describe a situation which pertains and which has not yet ended. But sometimes it seems to be used in the context of something that is expected to happen in the future but hasn't happened yet. It may be that the use of the negative would cover it.
The interesting thing is, about two screens later in the same lesson, I was asked to write the "yet" phrase in Gaelic and not as a question. I chose to put the "fhathast" before the city name just to see if that would work...it was accepted but showed an alternate answer that was as above. I suppose maybe both answers would have been accepted? Thanks for the response.