When I tried the API with the specifications (using Python) passing only minumum arguements,
the event was created successfully but never shown in the calendar (https://vrchat.com/home/calendar)
There was an issue on showing upcoming events in the group page so I thought it was a VRChat-side problem.
However when a fix got rolled out, this problem still existed.
Then I tried to capture the actual request made from the website and noticed
isDraft=false and featured=false are specified by default.
Adding these two arguments in the request fixed the problem.
So should these be required and default to false in the specifications?