I think you will have to use a method other than Mozilla to sign in to connect. I can use google and one other which I forget. Once you are signed in, you may be able to change your connected email account.

Evidently, adding a tag to a bookmark enables that section. In my case it's already there.

See also https://blog.mozilla.org/en/mozilla/local-translation-add-on-project-bergamot/

There's an issue with the Simplify Copilot extension which is being updated to fix it.

OK. It happens here as well.

I'm not willing to try it. Does your OS perhaps contain such a combination?