The user experience of the Firefox extension is usually nice: it is slow, but translations are generally better that the built-in translation of Firefox. That said, I've encountered incomplete translations here and there. It did not occur to me to record these encounters, so I can only offer one example right now.
The example is here: https://forum.shiftphones.com/threads/shift6mq-sos-7-0-l-20260127.7702/
While most of the page is translated as one would expect, the very first post is mixed. First, the screenshot of the original.
And here is the translated version. See how some text remains in German, and how the Overview table disappeared completely.
For comparison, here is the result of FIrefox built-in translation.
