I really like this add-on. It does something I've been searching for for ages. One suggestion I might make concerns the "Navigating in Tabs should open new Temporary Containers" option. It appears that setting that to something other than "Never" results in many websites that use redirects breaking, and requiring you to figure out the names of all the redirects and then putting the original website and the redirects all in the same permanent container with "Never", not set. This is a real pain, and a non-technical user probably wouldn't be able to figure out how to do it, so most people will likely set the global to "Never" in order to avoid the hassle, especially since you can't sync the settings across computers.

However, another side effect of having that set to "Never" appears to be that if you type a new URL into the tab yourself, the new site opens in the same temporary container. That seems to me to be more of an issue than allowing all the redirected sites to use the same temporary container by default, as the behavior the user is probably expecting is that each link they click on or each URL they type into the browser opens in a temporary container, but that stuff that's on the web page where they didn't manually click a link or type something else (e.g. redirects), would share the container. My suggestion here would be to either create a new option to allow the user to decide what to do if a new URL is manually typed into the command area of an existing temporary container, similar to the option given regarding the clicking of links, or simply assume that if the user types a new URL into the command area, that should be construed to be the same as left clicking a link and the same setting would govern both.

I think doing it that way would be a good compromise between maximum privacy and ease of use, as only the very technical and very paranoid would take the trouble to track down all the redirects and create permanent containers for every site with redirects that the non-Never setting breaks, and go through that exercise on every computer they use because the settings don't sync.