I had a Magic Robot when I was young. But DID figure out the secret and never let on. My cousins and friends thought I had this amazing general knowledge. Played it so often that some of the information stuck. It was very English biassed though. Until I got to North America (in 1989) I was convinced that the first person to fly faster than the speed of sound was Peter Twiss in the Fairey Delta II.
I had one of those too! As you say, very clever. Once I'd worked out how it worked, I kinda lost interest, but I used to amaze my young sisters by getting the right answers without the robot (the position of the answers was just offset x divisions from the questions). The main point is, in the good old days we could amuse ourselves with things that didin't even have one transistor in them! (and no batteries either!)
When this toy was sold for the first time, it should have been considered as magic!!
I played a lot with those "magic" books in which two bannana connectors were used for find the correct couple of question and answers -- countries, flags and so on-- But the use of magnets in this particular toy is really smart!!