Hi Ben,
I am not sure whether this will help, but I just learned of a workaround from Dashboard > Customer Management > Automations > New Automation. Select Pricing Plans and Webhook. I hope this does the trick! If not, we have a feature request for onPlanCancelled that you can upvote and comment on here: https://www.wix.com/velo/requested-feature/onplancancelled-event-required-for-wix-paid-plans
