I threw away my Hanna salinity checker. Would read different values for water in a container or water in the aquarium etc etc..
Salinity could certainly be a concern for corals going into a new system. I agree 70 for 2 days should not be an issue for anything in the tank. Something else up regarding that. As for the new corals I still think it's a shipping issue based on the speed you say they declined unless there is something really off with the tank but I don't really see an indication on that. Phosphates are kinda high but I have had them way higher and no problem with LPS. Pics of the corals close up and overall tank pics with white light would help a lot.
I would be careful using other peoples claims, or manufacturer claims to par level. What lights, power level and distance to water etc are you using? I would suggest renting or borrowing a par meter from a LFS if you can or BRS or local reefer. Some fairly reasonably priced meters on Amazon that do a decent job and I hear others use an app for their phone.. Not sure I would trust that but might be better than nothing.