you can also avoid the {{member.webinar URL}} token using the ON24 URL event and replace the event ID and Key with a local token. not ideal.
For tracking I was thinking to replace "https://webinartoken" with "{{member.webinar URL}}" or somenthing like this using velocity, haven't tried but when I get a time I will give it a go, I suspect it wouldn't work but worth to try
Tracking works (and you can speed your notifications) using the method described here: You don't really need to Wait for {{Member.Webinar URL}}
But what about email?