I am currently making a save game editor for Divinity Original Sin.
Ahhh, I was working on the same thing
Good lord almighty I want this so badly. I'm not sure what your limitations are as far as what you can actually edit in the saves, but if there's a way that you could include the capability to add spells and such to the characters, that would be awesome.
Both of those are possible with the current savegame format.
I see... perhaps it does make sense to work together: but is your idea for the UI similar to the one I initially proposed? I had a pretty set idea of what I wanted as an end-result to this project. I wanted a very user-friendly interface that was intuitive because it was familiar to the in-game UI. And if you did have the same idea in mind, I don't know how much use you would get out of anything I have written presently as it is not - at the moment - particularly modular, flexible, or production-quality (though I plan to tidy it up, in time).
Also, as an aside, I made a new save game yesterday to look at this new save format, but it did not appear that the lsb files were any different? Was compression disabled with the release of the hotfix?
The only difference I saw was that instead of <SaveName>.lsb, there were files sanity.lsb and meta.lsb.