I can't really imagine A12 being "bright", in fact it sounded a bit dull to me as it doesnt have the peaky upper midrange HD600 has. Ofc, that was my impression until I tried the cheaper V3 and realized all the details and body of the mids were gone
It's not a bright IEM per se, but you'll find its sound signature on the brighter side of things when coming from a Roxanne, especially if you're used to that smooth, darker tonality on a daily basis. The A12 has more clarity and extension in the high frequencies, so it might appear to be a little treble-oriented at first.