"Didn't around of a quarter of the bombs dropped miss the target?"
You need to define "target". The "napalm" bombs were not dropped on the actual ship, but on the oil slick with the intention of setting fire to the oil. This was a failure, as the oil was actually "floating" below several inches of sea water. Thus, we produced a lot of steam but few flames, and those that were produced were extinguished by waves.
"some of the Hunter pilots were trained on the Sea Vixen specially for this op". I am prepared to be proved wrong, but I have no recollection of this and I would be spectacularly amazed if it happened. Most unlikely.