You're right. I just tried this, into Japanese:

"I cannot believe you would say that to me."

It came up with:

私にそんなことを言うなんて信じられないわ

Holy crap, complete with a disparaging なんて, and a nice わ sentence-ender to make it a feminine sounding complaint.

I'm almost sensing like the thing is tying to tell me, "here is how your boring English sounds if it is turned into line from a J-drama."

Was this trained using subtitle databases, I wonder. It's as if a mediocre English subtitle was found, similar to my text, and the corresponding original line had been retrieved.