Getting a JSON file from AT3 is not a big deal. There’s still my Python script available that extracts the JSON part from AT2 and AT3 files. However, due to the complex AT data structure, the result is not easy to figure out, I’m afraid. It is a network of references that cannot be represented easily by a two-dimensional table, as the limited csv export shows.
See this thread: What is the data format of an *.aeon file?
If they aked me, I’d love to have a versioned, xml-based data format that is open for third-party software. However, I have good reason to believe that this concerns an insignificant niche and will not be put on the agenda.