Is this a feature request? ;-) As posted, I only have limited time to work on the project and try to fix critical bugs in time. Unfortunately, development is slowed down. To give a short update: I currently have a look on synchronizing with SFTP servers.
All error messages can be found in the log file. While JFS hangs goto the .jfs directory of your home directory and copy file "Log.txt". You may of course look into that file using the GUI if the program does not hang ;-).
Could you please provide a scenario of how to replicate the bug.