If you run in to the issue where an event that is shared with you is not showing up on google calendar it may have to deal with your availability and privacy settings.
If you are:
Available and Public: anyone able to see your calendar will see what event you’re attending
Busy and Public: anyone will be able to see your calendar event and see what event you’re attending.
Available and Private: will hide your event details and will not show a busy block. No one with this shared calendar will see this event.
Busy and Private: will hide your event details and will show a busy block of time for your event.