First of all: You only need to pick the language if you use the context-menu. You can instead use the "quick click" feature to translate with the top entry in your language list. You can configure it to be activated using a key-combo + click. Alternatively you can use a rocker gesture (tho I guess since macs only have one mouse-button, this is no option for you). I don't think I have a way to check for gestures like 3 finger click.
