The layout you described is called “quick Change” which is used only during the peak summer holiday travel period. During that period, the demand for business class travel is much lower, while the demand of Y travel is up for the holidays. So the “new” J cabin of AF was designed in a way they can quickly re-arrange the config, removing some rows of J and replacing them by some more Y seats. This is why you have this strange config of having some Y rows ahead of the W cabin.
To come back to your question about W seats, there are plenty of threads on this subject on this forum, so make a search and you’ll see. Basically the consensus is that it is fine for a day flight (your case), but not very easy to sleep in for a night flight.