To make it easier to edit character sheets (and exported game rooms since they are nearly identical), I've been working on an editor that understands the XML that they use. I knows what can go inside what, what properties it can have, etc...
This is a very early alpha:
<https://dl.dropboxusercontent.com/u/714 ... ed.app.zip>
NB: Requires OS X 10.7 or newer.
Note that there is also a good chance it may end up eating your file - make sure to work on a copy and keep a backup!
Future versions will get smarter about various content (for example, right now, all text is just text - it should know if the text is arbitrary text or a formula, and add formula specific tools, and hopefully at some point I can add a full UI editor/preview for working with character sheet panes, etc...)
There are unfortunately no plans to port this to Windows, etc...