@Developer Tools Engineer - Thank you for answering this question. I do understand that string catalog files are designed to be interfaced by XCode.
I would like to also bring your attention that there are other valid and relatively common scenarios where other tools need to read/write to this string catalog file. In an enterprise setting xcstrings file as well as other source code will be tracked in a git repository. This means that there are external localization tools via various integrations that directly read/write to this repository. If an enterprise is using an external tool to manage localizations, that tool can directly commit the changes to that xcstrings file without involving a developer or XCode. In fact this is the very reason enterprises uses external tools because not involving developer in every task increases productivity of the company.
You might say that you can export/import xcstrings file to other formats like xliff. However, that still involves a developer to manually do work and perform ETLs with XCode since xliff is not the format XCode ultimately uses.
Since this situation is actually relatively common, may I ask whether Apple can share the JSON scheme with the public? Apple is welcome to change the scheme at any time. The current scheme already includes the version information in the meta-data. You can simply bump the version to 2.0 and make the changes as necessary. Developer community can adopt subsequently.
Thank you for your consideration.