"Open" worlds you may transfer to. "Closing" worlds are enabled to transfer from.
Bullroarer is the public (Beta) test server.
Palantir is the private (Alpha) test server.
Note: If enabled, you may copy your characters to the test servers. Your characters will remain on their live worlds.
Enabling copy/transfer in launcher is a 3 step process:
launcher config: tells launcher (not) to show transfer button
transfer config: general information about transfer/copy enabled servers (basis for this page)
character data: fetched by launcher using your account id
Even if a server is enabled in step 2, it does not mean that the server is also visible in step 3. (i.e. your characters may not shown for several reasons)