Yes each scenario will need someone to design it, but you can get a lot of mileage out of each. E.g. consider the "place the missing power pole" scenario: manually build a factory with a few dozen machines connected to a couple steam engines with 20 power poles, then you can generate 400 playable puzzles/scenarios by deleting 1-2 power poles from the working starting point. Humans would find all of these to be equivalent, but I think agents need the explicit variation to learn the lesson properly.