I'm not sure how to ensure the FeedingIt update runsa as user if fcron starts it.

As for the log, I checked it and here are the contents. I don't see anything here relevant to update issues.

Traceback (most recent call last):
File "/usr/lib/hildon-desktop/feedingit_widget.py", line 140, in __init__
pixbuf = icon_theme.load_icon("feedingit", 20, gtk.ICON_LOOKUP_USE_BUILTIN )
GError: Icon 'feedingit' not present in theme