No, I don't know the size of the phone and keyboard in your photo. I mean how aethetically well balanced the layout of the keyboard is, there are all the four arrow keys, enough keys for language-localizing, etc. And it fits to a small size. Naturally I'd also appreciate an extra row of keys, but it may be difficult to build a 5-row keyboard for Jolla. If the keyboard slides out 70% or more of its total height, the remaining length of the rails may not be enough to make it durable enough (if you drop the phone + OH-keyboard, for example).
So, even though the French Azerty variant of the 4 x 12 HW keyboard would not be 100% perfect, it would match with the needs of most French people a lot better than the Qwerty/Qwertz variants of the same OH-keyboard.