The issue with the icon positions is a bug with different browsers and kml files, which are used for the maps on the hill pages, and the all hills map, but not your own Munro / Corbett etc. maps. The positions are correct, but the icon offsets are not being used to properly position the icon - sometimes they are ignored and so the icon is off below its true position, and then appears to move closer as you zoom in. This is an old problem - ironically some people who always saw them in the slightly the wrong positions now see everything correct for the first time
I get them in the wrong position on some hill pages and then correct if I refresh the page (on Chrome) and more consistently correct on some other browsers.
I've put this down to completely rewrite the code and perhaps no longer use kml files, but it's likely to be some time before the icon offsets are showing correctly for everyone in every browser.