GenStone panels are 100% waterproof so you would not need to worry about the front; however, always check into your local zoning requirements; For the water potential from inside the wall, you could attach Tyvek or a similar moisture barrier before attaching the panels.
GenStone faux stone veneer panels are made from a waterproof high-density polyurethane. More importantly, the material used to make GenStone is a closed-cell polyurethane. “Closed-cell” means the material is very dense. This density provides greater insulation and also prevents moisture penetration.