Liquid Glass is definetly a synthetic!(
MSDS)
I would prefer a synthetic like Prima Epic (
Prima Car Care: Premium Wax, Polish & More) over any carnuba wax for one reason. Due the oils in the carnuba wax it tends not to be as slick as a synthetic. Therefore dust tends to be more attracted to or stick more to a carnuba wax and synthetic has more of a dust repellant type property. Synthetics also last longer, which means waxing less often!
I have never personally heard synthetic sealants changing the properties of paint. But I could see that it may do this on a metallic based paint, maybe, but not really non-metallic.