I tried to install owncloud manually but i couldn't get up an working, currently it running by owncloud plugin. Do you know where should the correct pathway be?That log path looks like one for a plugin. All the instructions in this thread are about owncloud in a jail. I assume that fail2ban could be setup to work with owncloud as a plugin, but some of the paths would differ from those described in this thread.
Did you install the owncloud plugin, or did you manually create a jail and put owncloud in the jail?