I don't think so.
You can find all Notification in "Scripting Guide ADOBE® FRAMEMAKER® 2015 release" on page 741.
The one, that comes nearest is :Constants.FA_Note_BackToUser (34):
Meaning: Any user action, such as a command choice or text entry.
But I don't think that is what you are looking for.
Could you descripe what you are trying to achieve? Maybe, there's another way?
I've already tried Constants.FA_Note_BackToUser (34), but it is also called in other cases and cannot be distinguish, if the insertion of FM Variables is actual called event or not.
What I'm trying to do is handle simple insertion of variables from "Variables Tab".
You could also try Constants.FA_Note_PreFunction or Constants.FA_Note_PostFunction. When you use these, you want to monitor the value of iparm when the event is called. The value of iparm is usually unique for a particular function (like inserting a variable).
The Constants.FA_Note_PreFunction and Constants.FA_Note_PostFunction don't trigger if you use the insert button from the Variables pod. I can't imagine why not...