It's a rule that elevation data for highest peaks given by some API (e.g. Google) are significantly wrong. Resolution used is simply too low for high mountains to determine if cache is up there on the peak or hundreds of metres lower in deep valley. This skews quite much statistics about highest located caches - often hundreds of metres down.
In GSAK I have an option to correct elevation data manually, but don't know what would be the best solution for project-gc.