Translation:When was the train that we are waiting for supposed to be here?
There are (currently) 66 accepted alternatives, but only one can be the "main" translation. Usually -- but not always -- that's the one that sounds most natural in English. In this case, the translation shown seems like a better tool for teaching the Czech sentence structure, although it is not ideal in English. However, it's possible that this may be reconsidered in the future.