It's actually not that complicated and honestly if you use RO water and a balanced profile, the vast majority of beers come out great. Water modification have only a slight impact on beer IMHO. If you have a lot of iron or your water is very alkaline, that has a huge negative impact on the beer.
Your biggest concern is every brewers concern and that's pH. The pH needs to monitored and adjusted throughout the process, the pitch pH is often ignored by home brewers, but should be 5.1-5.2 for light beers (including IPA's) and 5.3-5.4 for dark beers. If you don't have a pH meter, don't sweat it.
I added a document to the post. It's a presentation I gave to my local homebrew club. At the end of it is a solubility chart for the various water salts.
https://docs.google.com/document/d/...ouid=108790144489096942341&rtpof=true&sd=true