I'm not sure exactly how you are intending to make the parts you want to paint, as I'm new to the idea of a terrace (a drawing would help me) but if there is a way to paint the "exterior" (the side away from the water and inhabitants) the results will usually be much better, as the imperfections will be masked by the light reflecting through the glass, and the scratching will be minimized. The Krylon fusion works well for painting plastics, including acrylic and PVC, and after it dries, all reports I have seen, and my own experience shows it to be harmless to the inhabitants.
For painting glass, I use the regular Krylon (or other "regular" spray paint), as it is a bit more durable than the Krylon fusion, but fusion will stick, if that's all you have available. It will take several more thin coats of paint to cover a transparent/translucent material than wood, metal, or the like, so make sure you get enough.