This actually isn't a great example: the Amish do use electricity on their farms. They just don't like to be connected to the grid, so they're big supporters of solar power. They probably know a lot more about electrical design than you think (depending on your definition of "electrical design"). They even have internet-connected computers so they can get orders from customers.
A better example might be hiring the Amish to lecture you on public transit design in dense cities. Not that they're opposed to it, but it's just something far outside their experience (they don't live in dense cities). Or back to electricity, having them lecture you about grid-scale electrical transmission, or nuclear power generation.