I was envisioning it as a steam engine, which might explain why it sounded so simple to me, yes. Like, 'this doesn't even really need a roll' simple, so I was kind of weirded out by suggestions to the contrary.
But if the engines work off of the big pile of explosions methodology I can see where the issue would be, fair enough.
A combustion engine is a lot more compact than a steam engine of the same power. Replacing the heat source of a steam engine is simple enough, and it has it's uses. Simplest would be the monitors on the river, but that's saving money rather than a qualitative improvment.
There's a lot of possibility for automation, like steam hammers, sawmills, etc, but the mindset isn't really there. An inter-karag railway, maybe out to our wolf friends, is another cool option that's not really dwarfy. Really, the Empire is much more likely to make a real use of it, but they don't have the tech yet. It's kind of a pity.
Now, combustion engines could work at least someonewhat, if you can figure out a mechanical trigger for a flashboil (or some other such spell, that's the least issue). Upping the output would require stronger spells, but that's possible as well. However, there's a second issue that
@BeepSmile pointed out: The enchantment running out of power after a number of activations. They can be recharged (see our room), but that requires Ashyq. In the best case, it could be supplied by a small fire of some large energy material. In the worst case, we need a powerstone.
There's two big issues blocking widespread adaption (assuming people are ok with magic engines, but I think that's a PR battle that can be won): First, making the enchantment itself, and also making it simple enough that it can be made by a lot of people. Flash cook is Relatively Simple, but the conditional aspect would probably push it up at least a level, so that's big hurdle number one. It's hard to get enough wizards to make the enchantments.
Related, if the recharging is a big problem, you either need the kind of fuel that means you could just run it as a non-magical engine, or you need a powerstone. And that's a very definite bottleneck (though those would be reusable, so you could accumulated a supply over time. A long time.).
Second issue is getting the engine tech. If the dwarfs are tetchy about the steam engine, then the next step up will be even more frought.
In conclusion, making a magic steam engine is a cool action we should definitly take. But I won't make a big splash for a long time yet (but when it does, we'll get to be ahead of their time, which is cool).
