The water tool and profiles in BeerSmith are incomplete and in need of updates.
You're correct that the distilled or RO water dilution doesn't show on the recipe, nor does it show in a water profile. You can only enter dilutions as a note and see it when you double click the ingredient.
Another issue is that minerals are all assumed to be added to the mash or full volume of water. There isn't a way to separate additions for adding to the boil. BeerSmith doesn't calculate potential mash pH, at all.
If you change your mind about the water profile, new minerals are left as they were from the first choice, not substituted. You must delete all water minerals and add a new profile to update the additions.
Essentially, minerals shouldn't be in the base recipe. They should be added to the brewday log version at brew time, once everything else is final.
BeerSmith is a solid and robust program, but this area is far behind modern brewer needs.