Hi,
Thanks for using our plugins. I can answer your question.
We do not have a feature to alert when an Event is been modified.
We have an alert only if a Community Event is submitted the first time.
It should be possible to create a custom function to do this, but that is beyond the support we can provide.
If you would like to request that feature please head to our UserVoice Page and add your own or upvote that feature as they will increase the chances of it being added to a future version.
http://tribe.uservoice.com/forums/195723-feature-ideas