Yeah, that's more of editing done to the data set of an existing tool rather than a new tool by itself.
Although I could see a use for a tool that helps build the changes to the CharTool data but that would be extremely game-specific. It's unlikely you'll see such a tool from us here at RPTools, but you might entice the community of users to create such a tool. Some folks here have taken to using other languages to build tokens from stat blocks, for example, so there is some local expertise for things like this. (Although this would be a much bigger task.)
There already is such a tool.. it's built into IT(or CT, I don't remember which.. perhaps both), but it has not worked since Jay did a largish ovehaul on IT back when he started CT a few years ago. Jay recently checked in some major changes to it which fixes many of the existing issues(but there are still some un-implemented features), but at this point, SVN and a development environment is the only way to get to the tool and even still there are some things that can't be edited aside from hacking the game settings XML file directly. However, we are SIGNIFICANTLY closer than we were a few months ago since it's been totally broken for 3 years or so and now at least SOME stuff can be edited.
Jay is looking for testers(knowing that there WILL be bugs!!!!) for the GameSettingsTool used to build/edit CT/IT game files, but so far, there have not been any takers that I know of other than myself(and I have not had time to spend more than a few very brief moments playing around with it in Eclipse.)