Even if the CDG-PRG were operated by AF instead of OK (and something's fishy in that relationship...I was booked earlier this year for AF-coded, OK-operated CDG-PRG later this month and then they just dumped the codesharing agreement, so I'm on AF metal for it), you wouldn't be able to be upgraded beyond CDG. Not that it matters, as intra-EU J/C is just Y with the middle seat blocked and maybe a real meal.