This is revealing one major limitation in the whole idea of "you can move servers any time you want": it only works if the servers are still up. If the server is down, and stays down (which at this point I don't know if it's going to be the case with venera.social) you can't move. You can create a new account elsewhere, but whatever's connected with the dead account is gone.
The #fediverse needs redundancy, methinks. Some sort of service that backs up account networks.