We don't change anything in the default runway light textures, we just use whatever is there in your FSX installation and, as I've said, KLAS doesn't have custom runway lights, they are plain standard AFCAD ones so, basically, they really can't fail.
Note that not all runways at KLAS have approach lights, only the 25's and 1L do, the rest don't have any approach lights other than PAPIs, check the charts.