If the name comes from *caru*, then
Carys looks like a good spelling, and not a bit trendy/made up, though
Cerys does, a bit. I've no idea how Americans might pronounce either one, but surely most of them would only need to be told once.
I like
Carys with
Heidi and
Griffin, but if there's any risk that people might guess at a pronunciation like kaREES, then I'd reconsider it as too close to
Rhys for comfort.
Isn't
Emily gorgeous? Excellent choice!