Absolutely amazing. I would agree that this definitely deserves a cartographer's choice award when it's finished!
As for your latest changes: Dökheim looks a lot better now, the shadow helps a lot I would probably place the stamp and the logo a little lower, especially logos tend to be placed more in corners. Since these two things are not part of the key it would also be fitting to separate them more clearly from all the beautiful explanations on the side.
Oh and I have a question: The "Schéma des Arrondissements" is currently aligned on the left, with the other key-boxes above it. But the Arrondissements-box is shorter than those, and "Ponts de L'Artère" (which is also a shorter box) is aligned in the center - did you do this on purpose? Or do you think it might look more even if the arrondissements-box would be aligned in the center as well? … Hm I have the feeling I didn't do a good job of explaining it, so have a picture:
Apart from that I think Argona is perfect. I wouldn't change a thing anymore if I were you, it is so amazingly beautiful, awesome and incredible!
edit: oooh I just discovered the Parc de Phosfère! Is that really a phosphor-park? What a lovely idea!