BA478 is scheduled to be an A320, so as these aircraft are all converted (or are otherwise ex BMI airframes), there will be no converter seats.

Ignore Seatguru because it's appallingly out of date.

I would not pick a seat on a route like BCN near the front of the ET cabin as the CE curtain is likely to shift back due to upgrades, and you run the risk of ending up in something silly like 18E.