Hi Andrew
Thanks for updating the thread.
I'm not sure what's going on with the backup timestamps, I'm not aware of anything that's changed in that area.
I'm afraid the second problem is more problematical: the API that I had to drop to enable AMO to approve TiddlyFox again was the API that was used to remember preferences in older versions of Firefox (where the new preferences API is broken for local files). So, the price of inclusion in AMO was to have a much worse user experience for older versions of Firefox, but a much better experience for newer versions. It's all a bit frustrating.
Best wishes
Jeremy