Yep, the map at the top of the home page is missing a lot of tentative sites, mostly because the data isn't really available for many of them in a usable format. I did go through and slowly create some of it (I did the new German T-list sites). Unfortunately my laptop and its back up were stolen, so I have sort of lost the impetus to redo it at the moment.
I will aim to update it at some stage, but I haven't had as much free time in the last few months. I will certainly be aiming to update the inscribed sites on the map soon after this year's meeting. As soon as I get a new laptop anyway.
In regards to overlays with the actual site boundaries this is a surprisingly large task. I think with a bit of work we can get many of the natural heritage boundaries from Protected Planet
, though they have changed their set up in the last few months and I can't quite get the information in the way that would be of most use to me for the map.
In regards to boundaries for cultural sites, in most cases these don't exist. I have them for the sites in England (Thanks to Historic England) and for the Czech Republic (because I drew them by hand myself).
If people out there know of national/ regional heritage bodies that keep boundary files in a .kml or .xls file then we should be able to incorporate those.
Sorry that isn't the best answers, but hopefully I an find some time to improve it.