You can search for a soldier name to find the soldier entry, and from there all the other values you can change. The format of the file is basically a raw dump of the save, so you'll need to search for whatever it is you want to change. You can edit this with a text editor like notepad++. Just drop a save file onto xcom2json and it'll create a. Maybe some day I'll actually finish the gui part but don't hold your breath, I hate designing UIs :) The json versions were just a proof of concept to ensure it works but I never had time to go write a full-fledged GUI for it. Yeah they are not easy to use by themselves, so sorry in advance.
