I think this may be useful to Spark developers: I have created an updated Italian translation based on the SVN (9710) English translation. The line ordering is also the same of the English file, so future missing strings can easily be found using a diff software.
Also, I'd like to point out a small mistake in the control labeling. In org.jivesoftware.sparkimpl.preference.notification.NotificationsUI, the betaCheckBox control displays the text:
betaCheckBox = new JCheckBox(Res.getString("menuitem.check.for.updates"));
while the appropriate phrasing should be something like "Check for beta updates", so I suggest creating an additional string in the language file.
Thanks for this truly great piece of software. I hope this is the right place to post my contribution, but if I'm wrong I apologize and humbly ask you for the correct location.