How is this programming rather than just learning how to recognize musical notes. Also, would this then start to associate these colors with these notes in any weird ways later in life? I'm not talking synesthesia or anything, but I can remember the music I was listening to at the time of reading a book or think of the book when I hear the music. Unless, that's the programming
1 cent: Every hit is an atomic action that is causing the robot to take a certain action. Furthermore, all points in that maze has a decision (from at most 4 different choices) to make. So, hitting on a note (making a choice) is like writing an if statement. Furthermore, you can ask them to come up with the color combinations to hit before hand and try to run it all at once. If it fails, you do it again.
2 cents: Since this is designed for 2-3 year olds, if statements make a good basis for starting programming or logic in general. As they grow older, we can introduce loops and functions.
Moving on to the next question about starting to associate colors with notes although avoidable by randomly assigning colors to the notes (glue and paper), is possible like you said. However, I would like to claim that it will only stick (no pun intended) if the same colors play the same notes for years, if not months. Which given how two year olds are, is highly unlikely. They are done with a toy in about a week or two, max a month, give or take.