Putting aside the work itself of creating a UI (this is just a simple install guide), that's not possible without exposing the encfs keys to the remote server. In this setup the client data is all encrypted before it reaches the server. The server is just a sync point for multiple clients.
You could have a UI (web or otherwise) on a separate client but it would have nothing to do with the server. It would just be a client that provides a UI interface to the decrypted encfs filesystem.
You could have a UI (web or otherwise) on a separate client but it would have nothing to do with the server. It would just be a client that provides a UI interface to the decrypted encfs filesystem.