Just following up on this: any news on the Safari extension being reintroduced. As far as I can tell, this has always been a signing problem. Apple's been doing a great job of protecting its users from installing bogus extensions. We just need GTM/LogMeIn to get their extension approved by Apple.
Safari 12 in macOS 10.14 Mojave will be blocking all unsafe extensions automatically. No good way to even install their unsigned stuff.
As a developer for Apple products, it's pretty imperative that I use and support native macOS apps like Safari. Would love to see GTM fix this bug.
We recently released a new GoToMeeting G-Suite Add-On for scheduling in Google Calendar. After you install the Add-On you will be able to add GoToMeeting conferencing to your Google Calendar meetings from any browser!