That crown uses a plug that goes into the top of the blade, maybe about 1/2" of insertion. I suspect the pock hole is only in the brass at the blade's end and doesn't go all the way down into the brazed joint. Have you tried to push a piece of thin wire into the hole? That the steerer wasn't fully inserted into the crown is another indication to the builders having had a "good lunch".

I've seen a lot of really messed up Raleighs, build wise. Generally they don't have failure issues, just ugly joining. A few are worse and have pulled apart. Without destructive or "aerospace" methods I don't think you'll really know your answer, will this fork fail during use? I would be content with easy stress testing and then keeping an eye on it thereafter.

To fix is to first find out what's really going on. So we go back to either destruction/taking the fork apart or some form of scanning to know how much filler is present (and the failures I've seen are almost always from a serious lack of filler penetration in the joint). Easier would be to build a replacement fork. Andy