cybereality you can use LibreOffice Calc (or Excel) to write the data, then export as CSV.
Not really, except maybe for testing.
The idea is that the first phase (designing the tactical doctrine) should save each tactical doctrine, and that the tactical doctrine can then be used with various fleet composition.
So the ability to save to the format is paramount.
I guess JSON it is then, since I don't really need to save any Godot object.
Maybe I can use CSV for ship data though, since these ones are not to be modified by the combat system (in FreeOrion they are designed in separate panels), and the mock-up only needs to read them.