Google Translate saves all of your previous translations in a handy list (first pane). Except, it doesn't save most of mine!
Start typing, and you'll get the translation immediately (second pane). No good reason to press "Go" at that point, so I never do: I got what I wanted.
But only pressing "Go" constitutes a complete action of translating, and only then this translation will be saved into the "Recents" list.
One feature of Google Translate hurts the other.