The gibberish you're seeing is how Orchestrator translates the published data and variables to the database guids. Copying this out will always translate to the DB guids, so there's no way to do a copy/replace with "activity name" for "Error Summary". You'd need to subscribe to each activity's data or look up all of the guids which probably wouldn't be easier.
Unfortunately, setting up the error handling process in SCOrch becomes tedious to be effective.
I use a separate email linked to each activity to give more information based on the error message. I don't like to use generic error emails with published data from multiple activities since it doesn't necessarily give all the useful information you need (or an end user will be able to understand).