The editor data path should be :\whatever\Divinity - Original Sin\Data\Editor\ (with the game data path as :\whatever\Divinity - Original Sin\Data\). I believe the editor data path just points to the Divinity Editor's tools and settings and mod-specific data files, etc.
I've never had to touch or mess around with anything in \Data\Editor\ before. I've left it entirely alone. For the most part, as a user, the mod is loaded from \Data\Mods\ (as well as from \Data\Public\ if any .txt customisations are necessary). There are specific \Data\Editor\Mods\ files there, but that info only appears to be pulled when opening in the Editor (they won't be used in a published .pak of the mod. That said, there is an autosaves folder present in \Data\Editor\Mods\.
From looking at my own files, my best guess would be that you definitely need a MODNAME entry for \Data\Mods\MODNAME, then maybe the associated MODNAME folders in \Data\Editor\Mods\MODNAME\. You can also open up a mod in the editor if you have a .pak in the documents section, without the folders in your \Data\etc folders.
I don't know if any of the above is useful to you, ha.
