Hmm, I'm actually seeing that here too now - looks like a bug. Fortunately, as 2.0.1 isn't final yet there's still time to fix it in that, so this should be corrected in the finished 2.0.1 release.
"Trad-only" gets rid of the [--] brackets with the simplified character version of the headword; in regular "Traditional" they'll appear however they're configured to appear in the main dictionary, but since some people might prefer not to be distracted by them when reviewing flashcards we provide the option to get rid of them in those.