I know that workflow email templates can be extensively customised but is it possible to add standard content such as wording or modify the standard meta data fields that are displayed in the EBS workflow notifications that the user see's in the web browser?
Instead of modifying the standard Notification, I suggest to make the copy of the Notification like..
Ex: standard Notification Name is stand_not, then create custom Notification like XX_stand_not
Upon creation of the Custom Notification, proceed with the desired changes and use the Notification at the required Context.
Hope this clarifies you doubt.