The problem quickly goes from bad to worse and the solution may be no improvement over the original problem. If Microsoft were to develop some automated way of fixing this, how would the automation know which of the versions of Heading 2 was the correct one? What if it chose incorrectly? Now, multiply that by a dozen or more different styles you need in the document.
For just one instance, let's say that you have (as you say) a dozen versions of Heading 2 in the document. In fairness to Microsoft, it is not a problem that is really possible to fix. Editors of various stripes have been struggling with this problem for years, and it is not a problem that Microsoft has been able to fix. The reason is because, literally, you are trying to unravel what has become a bowl of spaghetti. Seriously, there is no quick way to do what you are asking. Given the three requirements (easily, quickly, and safely), the old adage comes to mind: You can have any two you want, and two out of three ain't bad! Fred wonders how he can easily, quickly, and safely reset and make all these styles consistent. Fred has a 60-page legal document that has styles from all over the map (such as a dozen versions of Heading 2, numerous tab distances even for the same level of text, etc.).
