@monkey123
That they are...
Steam engines and steam turbines are technically different things if you want to be pedantic about it thought.
I just said engine to make it easier to understand for the people who have no idea how a steam engine and turbines even work.
The biggest two problems with steam-powered trains were/are that they only were efficient when going fast, and they dropped efficiency the slower they went.
And also that it took a long time for the engines to start up as it had to be heated up before it could start running making the wait time waste fuel.
This meant that trains that had to start and stop often consumed more fuel then trains that could keep chugging along for long periods of time.
To the point, it was no longer economic to use steam engines anymore after fuel and later electricity-driven trains were invented.
The pre-heating might not sound like a huge problem but it caused a chain reaction of a lot of other minor problems and downsides that it wasn't worth it anymore.
If we want ( and we actually did back in early 1900 ) make a good steam-powered train you need to find a way to store the excess energy when the trains have to stop.
Or to find a way to only use as much fuel as you actually need and remove all wasted heat, magic crystals made out of pure energy could easily fix both of these problems as long as they aren't radioactive.
( at that point its basically electric power anyway )
Heck if we could actually make a battery that could store huge amount of energy efficiently it would make it possible to actually make nuclear-powered trains without the energy lines.
Modern trains are technically already nuclear power because they run on electricity that IS generated by nuclear power.
( or some other means... if you want to argue semantics you can call solar power fusion energy )
its semantics really...
I just wanted to point out that magic easily could make steam engines viable even in a somewhat modern setting...
But then again that's just nature of magic... it can do a little bit of everything if you want it to because its fictional.