Hi -- thanks for using the newly relaunched forum!
While you can edit the .json files manually as they're just structured text, that is not the intended way to use them. The reason you see some irrelevant fields in the json files is that internally the reference material data are stored as "results" just like other results (e.g. the ones originating from your data). For RM data some of the fields do not make sense.
In iolite 4, we would encourage iolite 3 reference materials to be brought in via the Tools->Import iolite 3 RM file menu item. The data can be subsequently edited in the "Reference Materials" section of the "Data Browser". If you have any issues importing an iolite 3 RM file, please let us know. Most of the time if there is a problem importing it is due to small formatting errors that are easily fixed in the original file.
All the best,
Joe