Hmm people seem to be confused. Cork is really the necessity in the middle, Norwegian want flights from BCN-BOS, but can't do it on a 737-800, that coupled with the flag of convience makes Cork a good stop. Why would they stop at SNN or DUB who already have a largely supplied BOS market?
Also the times are probably wrong there Charlie, the aircraft is based at either BCN or BOS and they will have the longer stops for crew change etc. Cork will only be a small stop on the middle maybe 40-60mins