My only wish was that I can force it to always allow me to try translating things, even if it doesn't identify it as some specific language. Sometimes what I want to translate is like 30% one language and 70% another language, and I still want to translate it to another language, but since the tool doesn't see it as "foreign enough" or something, I don't even get the choice of having it translated.
Besides that, it's a wonderful despite it not being perfect. Hopefully with time it'll only get better as they get more data. On that note, I'd be more than happy to contribute data if they added some way of giving "good translation / bad translation" feedback, but haven't seen that. I guess I had two wishes in the end.
You can, but it's somewhat hidden. Open the hamburger menu in the top right, then select “Translate page…”.