Sorry for the issue you had. Sadly when Firefox crashes sadly many strange errors can happen to the Firefox profile as well and sometimes (very rarly) even to profile storage data (like bookmarks). Of course that I can't fix since it has nothing to do with the addon itself. As regarding the Multi-account container, simply I have my hands quite tied because there is no reliable way of storing anything beside a bookmarks. Whatever storage I might use, be it local or cloud based on profile a lot of strange issues can happen. For example local storage is deleted right away if you disable an addon. That's means you can only rely on it if it makes sense. But having half of the data stored in bookmarks and half in another place is very problematic when the other place is wiped out suddenly :|. Sorry for the missing feature, I might be able to find a solution at some point but I can't tell when it will be implemented.