I booked a flight in BA J for Oct 2022 to CDG and beyond, Of course its not directly out of SEA since there is zero J on BA out of Seattle available pretty much the entire last half of 2022. You might try looking for awards out of AA or IB gateways. I have found flights available (like on Finnair out of DFW) but it wont show on a search because there is no low award flights available on AS so getting there requires a different reservation. And yes, BA has expensive surcharges but its way better than paying for J generally speaking.