It's just a matter of knowing what those fields are called and you can go in and edit them. So somewhere in that JSON there is an object that represents a soldier, and somewhere else is an object that represents your HQ state and has your money value in it. In EW the saved game was basically a snapshot of your game state. The bad news is that a raw JSON format is not as useful for XCOM2 as it was for EW. I never fully understood the file format entirely, so there are still plenty of 'unknown' fields. It didn't require a huge number of changes compared to EW, but there are a few things in different places. The good news is the save format is very similar to EW. Warning: Long technical detail post below.
I didn't get the other direction working yet. The latest (from a few weeks ago when I looked at it last) is I successfully parsed and generated a JSON file for a single sample save game. I started on an update to XCOM2, but it's been constantly pushed to the back burner due to LW2 work, unfortunately.
