I would advise against calling
obj.emit_signal on another object like that. Signals are emitted from objects themselves, not a third-party.
If you know how to either detect the click or the enter key on your area, one way would be to attach a script on it to customize it.
That script would detect both clicks and enter key, and emit a custom
activated signal when it happens.
Then, you'll be able to connect behavior to that signal, without having to mess with what could have triggered it.
Having your game logic directly do that without intermediary signal would work too though, as long as only one scripts listens to it.