Well, in addition, many of the markers on the map are what you might call "legacy" markers - they were placed when we were still on the old forum so the names are from the old forum. Some people have either continued to use the same name or contacted me to tell me what their new forum name is (and I've changed it), but many others have not. I suspect a number of the older ones simply are not active here at all any more.
That said, if it is a current forum name, you can find them using the search function here (the magnifying glass symbol in the upper right). If it is a current forum name, putting it into the search will get you a link to their profile here and an opportunity to send them a private message. If it is not current, the name will not show you any results. Beyond that, I don't know.