The size of the train bags the question, is it efficient to build trains that huge? It is as huge and wide as a building and the though to a whole city-building-lineup cruising through the lands is charming, but...
First of all, is it economical worthwhile? While one could argue, that a larger size means more seats to sell, you have to sell them in first place. Given, that the trains depart very seldomly, connects places very far away and mainly visits major settlements, it might work out with a reasonable ticket price. We just don't know enough about the circumstances of that world. It seems a bit excessive, but then again hurling giant metal birds on intercontinental flight in a huge number like we do, might look excessive from the outside, too.
Secondly though, what about the technical feasibility? That's an enormous build. And magic aside, if that world works nearly the same way as ours, then that becomes a "massive" problem. The perpetrator is the strength-level of electromagnetism and the correlating inter-atomic bond-energy (how strongly atoms and whole molecules are bound to each other). A worker-ant falling from the empire-state building wouldn't even get hurt badly or at al from the impact, while an elephant would break most likely quite a bones when falling "only" 3 meters (heck, even a human might). Simplified (into only 1 dimension) a chain is only as strong as its weakest link (inter-atomic bond). And if you have slender builds, the longer they are, the higher the chances, that a region happens to form with a lot of weaker bonds in a very unfavorable distribution or even with a structural fault (a bubble, tension stress, small rips). To cover that you have to make things thicker. Compare a large Dinosaur's leg bones thickness to the size correlating thickness of human bones or even the bones of a mice, and you'll see it. High buildings, like skyscrapers do exist because of the wonders of architecture. And they don't move through the lands. Such a train would be massive. It's weight increase would be considerably bigger than just its increase in volume.
-> Which brings us to the next problem: What kind of trails is that train supposed to go on? Normal railway steel-beams would simply be flattened. And even bigger ones would be deformed over time (jet again inter-atomic bond). I imagine that the pressure of the weight of the locomotive would be enough to give semifluid properties to steel. (It deforms, maybe even no matter what). Those beams must be massive and might be made of some stronger metallic alloy. Damn that trail must be unusual expensive. (Again the economic POV.) -> They should have gone with normal sized trains.