I tried this:
:*:test`n::bob
And it types bob no matter which enter key I push. If you use n, that doesn't necessarily indicate that you are pushing any
enterkey - it just means you are inserting a carriage return - so either
enter` key will do that. But your text area must be able to receive and insert a carriage return.
That means, that if you are working in a single-line text box, it can't receive a carriage return, in which case, using `n won't work for you.
You might also assure that the active window is able to receive ^!u and do something with that.