What's the proper way to address a moisture issue in a concrete slab?
A plastic or EDPM rubber sheet will work, if the flooring installers don't puncture it. That pretty well limits your flooring to a floating floor, but that's not a great impediment. 

Nothing  painted on to the inside of a concrete structure will stay put if water is coming from the outside (more commonly seen as failed attempts at "waterproofing the inside of a basement" but the principle is the same. Painted on products only work from the outside.

On the other hand, if you have actually resolved the sources of moisture, there should not be any more.