There are some things that show up on screen already translated, and others that don't get translated unless you press the translate button. That basically means if translated data has been saved, it's being reused.
In other words, when something already translated comes through, it means someone with the same native language was interested enough to translate it. It's not as strong as a Star, but it might serve as some kind of indicator.
Translated from Japanese
commit ceb4d71
now that you mentioned it, that's actually clever on the part of /dev/null team. show original for fewer translation request, if somebody translated it then store, then serve the translation moving forward