[MrWarper]

More details, yes, I think I wasn't extremely clear...

Once you open a file located inside <...>/<first>, <last>, go to the application menu Options -> Save preferences (I have auto-save preferences set to OFF), and exit Xournal. <blah blah>/<first>, <last> should be in your config file now. (At least that method works here, and I suspect that's how I first bumped into this.)

If you start Xournal again via a shortcut (without invoking it on a file), and you go to the app menu File -> Import, Xournal will try and show the contents of that directory in the file open dialogue. If it has replaced the comma with a dot (as it does here) it will show you a message error (correct - it is trying to access a non-existent directory) and list its parent directory contents instead.

Edit: This path ended up in line 38 of the config file, 'default path' under '[general]'

--trim, trim...--
[general]
# the display resolution, in pixels per inch
--snip, snip..--
# default path for open/save (leave blank for current directory)
default_path=/media/mmcblk0p1/e/Enguídanos Usach. Pascual
# use pressure sensitivity to control pen stroke width (true/false)
--cut, cut...--

Hope this helps,