There were a number of minor problems...
your sprite font should be 16x16 (not 20x20)
the animation speed for Cadenas was not 0, so it was playing the whole animation. You want it to stay at the frame you assign, so it should be 0.
You want to unlock levels Less than or equal to Niveau
In VerificationReponse, you want to check if every piece in the puzzle is set to the correct colour, so you need a for each Element loop, and if the number that are correct matches the total number of Element, then show Victoire and go back to the menu.
oh, I added a TextInput box in the top right corner that shows what each piece is set to for debugging... so I would know what to set each piece to :)
Edit: the family instance variable was being set correctly. It was how you were checking if the puzzle was complete that was the problem.