Thanks for your input.

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.

Hope this helps.
Kind regards.