hey guys - I never imagined when I first made my little Championship manager attribute editor that it would result in something like this so many years later. I'd be more than happy to help. A couple of things I can chip in with:
regarding the editor not recognising the file - as well as the official releases of CM, there were a few releases which had small changes, presumably with each production run. So we had to build that into the system, to allow the editor to recognise which game you were using, because the data was stored in different places. If I can get at the source code I would be able to remove this problem.
One of the other things I have, not sure if it is in the download release, is instructions on how to change all the background images and loading screen. You would be able to add modern images of players like Rooney, Drogba etc.