Hmmmm.... no others had this problem or can at least verify there is a problem?
I would like to go grab the stuff I missed there but can not....
This from a wiki...
Under no circumstances should you fast travel to Japhet's Folly by yourself and not following the Rise in the East quest. Japhet's Folly is it's own "world" in the game and once you are there you cannot fast travel or leave in any way other than ending the quest with Adelaisa, who wont be there if you fast travel there on your own. (After I beat the main quest and most of the factions I turned on all the map markers and was just messing around checking out random places I hadn't been and I lost 1.5 hours of gameplay because I had to boot up an old save after going to Japhet's Folly, you can't leave that damn place no matter what you do.)
Note: You can avoid being locked in Japhet's Folly by using the console command: coc QAsmoke to teleport to the developer's room. If you then use the command coc Riverwood, you will be teleported to the mainland.