Seems like CSV would've been a better format than JSON for this type of data based on the screenshots.
Indeed. Your typical data requester isn't going to know code for working with JSON. And converting JSON to CSV is a pain.
Also, CSV can’t easily handle nested objects. If the data model is even slightly more complex than a plain table, it doesn’t make much sense. I’d also argue that even if the source data is stored in an RDMS without exotic data types, a JSON with a nested object representation is probably going to be more friendly even to non-developers than multiple files with opaque foreign keys linking back and forth.