If you use google chrome, this extension may be useful to you.
Keyboard Shortcuts for Google Translate
It allows to use keyboard shortcut for Google Translate on Web.
[Option](PC:[Alt]) + [0-7] keys are binded each indexed buttons. - lang-swap button -> Option + 0
- button1 -> Option + 1
- button2 -> Option + 2
- button3 -> Option + 3
- button4 -> Option + 4
- button5 -> Option + 5
- button6 -> Option + 6
- button7 -> Option + 7