@NiLuJe: ok, I updated LibrarianSync to use the format you described in the old thread (btw could you move, as you volunteered, the relevant parts of thread
https://www.mobileread.com/forums/sho...d.php?t=160855 to the new one
https://www.mobileread.com/forums/sho...d.php?t=245691?)
The json file should be named calibre_plugin.json and be in the extensions folder.
I tested it on a hand-written json, it seemed to work. The timestamps and locale are not used by the script.
@knc1: I agree exporting the collections could be useful, I'll see what I can do.