Caiomhe is one of my favourite names. I'd use it for a kid if it wasn't too close to
Geneva, which I like more.
I don't find keeva or kiva attractive at all. Dumbing down this name ruins it for me.
Yes, the spelling could be a little problematic but heck,
Caitlin has so many spellings that you'll even have problems with that one. I've seen people screw up the simplest names. So I'd go with the original spelling. In Aus
Sean,
Lachlan,
Niamh,
Siobhan - these are all pretty mainstream.
Ella went to school with a
Saoirse,
Caoimhe,
Tadhg &
Aoife, ands liv went to gymnastics with an
Aoibhe and everyone managed fine.
So I say go for it.