I can't (and don't want to) picture it on a girl, probably because I'm so attached to
Mikael and
Mihail and
Mihael and
Michael for boys. I'm also pretty sure it would be often confused with
Michael, unless Michal-on-a-girl is common/usual where you live. It might be best just to use it as middle name to avoid confusion. Besides,
Kassandra Michal is quite pretty. :)