...
Google calendar is notorious for long update delays of up to 12 hours or more for subscribed calendars and you cannot force it to update. If the wiki calendar has been refreshed and the meeting in question matches what you see in Groups.io, the only way to force g-cal to update is to actually remove the calendar and re-subscribe. This is a known issue that the LF does not have any control over.
Where to find more information on Confluence/Wiki Team Calendars
Visit this link for more information on Confluence/Wiki Team Calendars: https://confluence.atlassian.com/confkb/understanding-time-zones-and-the-display-of-event-times-in-team-calendar-806457993.html
All the meeting times displayed on the wiki are wrong
As an anonymous user the wiki will display times in UTC. Make sure that A) you are logged into the wiki and B) that you have set your timezone in your profile.
All the meeting times displayed in Groups.io are wrong
The default is UTC. Make sure you have set the timezone in your account profile. If the calendar times don't match the time zone you are in, check your Profile Settings (and be sure you are logged in). More details available here: https://confluence.atlassian.com/confcloud/edit-your-user-settings-724765386.html
How do I convert my time zone to UTC?
...