[Darknemo2000]

Steam engine can perfectly work without her. Heron described the steam engine principle and thats way before the middle ages in our world. Heat is essential for steam engine, but just plain fire and not Anna's fire could have worked just as fine its just the making of the actual steam engine would have taken a while.

What I see Anna's power is something that sped up the Roland's industrialization but wasn't essential to it.

Yes, thanks to the story, plot timing is everything thats why Anna's power seems like super uber important (and timing wise - it is) but in reality Roland could have achieved most of those things himself just at a very slower pace. He would have lost pretty much all of the witches though without her.