Just got the follwing gem from Google Calendar Sync:
As a result of the sync operation 29 events will be deleted from your Google Calendar. Proceed with the operation?
The obvious problem here is that I am not provided information sufficient to make a choice. The only way to find out which events will be deleted is to click “Yes” and see what happens. †
I realize this was probably someone’s 20% project, and it’s beta software, blah blah blah. It still sucks.
† Actually, I still have no idea what the hell was deleted. If I’m late to your party, consider this a preemptive apology.
I know this doesn’t resolved your qualm completely but I’ve noticed that this happens after an archive of my mailbox. Google Sync must not notice these items were deleted until it does a full sync. So, what is deleted should match your archiving rules. You’re right though, it doesn’t give an itemized to-be-deleted list.