Xenia (ZEE-nah) seems silly, I'd say go for
Xena instead. I mean, why put the i in altogether if you're not gonna pronounce it? Mispronouncing a name on purpose is just asking for trouble for the child.
Caoimhe is nice, but the pronunciation would cause a lot of trouble (or the spelling when she said her name and someone has to write it down).
Caoimhe wouldn't work on a non-Irish child I think, I'd recommend using
Keeva instead, if it's the sound/meaning you like about the name.