How do I edit events in Apple calendar?
Edit an event
Change event details: Tap the event, tap Edit near the top right, then in the event details, tap a setting to change it, or tap in a field to type new information.
Can you see when an event was added to Google Calendar?
Find the Google Calendar event details
There's a lot of information in that file (especially if you've got a lot of events!) but for each event you will be able to see the date it was created as well as the date it was last modified. To find any particular event just search for the event title or details.