If you create an exhaustive list of all the possible inputs, this list could be used as a lookup table to map your desired input back to the output.

Since the list of inputs is so large, you'll want to find ways to remove the redundancies in the list. You can think of the various AI techniques as being clever ways to make the length of the list smaller by using perl code.

Take a look at all the Lingua modules, such as Lingua::Stem. Some of these modules are quite inspiring!

There is nothing wrong with working on a 'grand challenge' type of problem, even if you are an amateur. I have worked on some of these challenges. When I get something working reasonably well, people say something like, "Oh, of course, if that's all you want, it is easy. The really hard part is..."

I'm not saying it's impossible though. You could certainly scan a text for sentences that fit a certain predetermined structure for parsing, but it seems to me that making full use of random texts will require some kind of intelligence. That said, I'm also very interested on any other input on the topic.

some "brute force" strategies to help someone change BEFORE into AFTER, while minimizing the amount of 'hand editing' necessary.

Oh, you only want to minimize the hand-editing necessary, not eliminate it. Yes, that's a much easier problem. Copy and paste will help for starters. It's also pretty easy to write tools that will do things like capitalize the first letter of every sentence, so that you don't have to fuss with that when you rearrange sentence parts so that the first letter is not the first letter anymore. Using a full-featured text editor (e.g., Emacs) will help considerably too, since you can do things like bind a keystroke to highlight forward to the next punctuation mark and cut or copy the result to the clipboard. (Then all you have to do is go paste it...) It's actually pretty easy to get the computer to do a lot of your editing work for you -- as long as it doesn't have to decide what editing to do.