My issue is kind of similar, I use a German operation system but have everything in Firefox set to English. The translation dialogue target language defaults to German, but I feel the translations sound clunky. I want English to be the target languag...
I edited this post; before there was a complaint here about the "thanks for loving Firefox" welcome tour wizard and its slow animations and that it couldn't be skipped. I just found out it's just another browser tab and can just be closed.
