Sounds like you've developed the same reaction to salt as I have, maybe even more pronounced. I'm still good with garlic however, and pray that doesn't change.
For Kosher Salt I used Diamond Crystal and, thinking about it, I may have screwed up as I used 1/2 cup, but did not weigh it. Morton's KS is much more dense than Diamond Crystal's, and when substituting one for the other, the ratio is approximately 1:2. In other words, assuming the 1/2 cup of KS called for in the recipe was Morton's, I should have used 1 cup Diamond Crystal. If that were reversed, you should have used 1/4 cup but, you weighed it so there should have been no error on your part. In short, I may have not noticed the salt as you did because I was using 1/2 of the amount called for.
It's a gentle reminder to myself to get back to using weights when making brines rather than going by volume.
Mr T's recipe clearly specified the weight, but most recipes do not. It would be a big improvement to specify the brand of KS being used when a recipe calls for a certain volume of it, but the weight is not given.
Your brine, pellicle development, and smoke times were pretty similar to mine. The only major difference I see is that I soaked the fish, and you didn't. That could make a big difference with something as porous as a salmon, or any other fish for that matter.
I suggest you go back and review the the salt to water ratios of brines you've successfully used in the past and see how they compare to this recipe. You might get some guidance for adjustments on future attempts.