Me and my sister got in a little fight last night over it. She sagte Du pronounce it like 'Cone' because the Dub of Bleach says that. But I sagte dubs do pronounce names wrong sometimes. I sagte Du pronounce the 'K' and then say 'On'.
Du kind of just answered your own Frage there... In the dub, it is pronounced as 'cone', but in the subbed, it is pronounced 'Kou-na', oder 'K-on' - at least, that is how I figured I would translate it. Du see, it depends on how the series has been voiced and such. I think, technically, it would be the Japanese version, as opposed to the dub, because the name is supposed to be a Japanese one.