I love Cassiane and I absolutely agree that Kassiani would read tryndi. Cosima, Verity, Marian and Cassiane are my favorites. I think that they're unique but familiar, lovely, and not too difficult for an American mouth to pronounce. I just love Noor in the middle spot for any of them except Cosima, because now that you've said it, "Cosmic Manure" is all I hear. Cosima Maris or maybe Cosima Theophane?
I thought at first Cassiane did end in the "ahn" sound but I like it a lot now that I know the real pronunciation. I think it would go well with your son's name.
I agree with your spelling of Cassiane. It's much nicer than Kassiani.
My favorites are
Anastasia (although probably too close to Antoine)
Nerissa (maybe you can still convince him that this is a name)
It's a girl? Congratulations! That's lovely.
I think my favorites are the C names, Cassiane, Chrysanthe and Cosima. Bonus points for Cassiane, since your husband loves it too, though I think my favorite of the three might be Chrysanthe. With my naming style, I'd probably put it in the middle, but I'd be thrilled to see it used as a first name.
Kyriake is fascinating. It's loads of fun to say, and I like all the lovely history behind its meaning. I wish it didn't make me think of the word "karaoke," though, and I think Americans may have trouble with the spelling and pronunciation. Keep pushing Kyrielle--gorgeous.