The "He" here is really throwing me.
Would a more literal translation would be "The cute sister is yours."?
It's unnatural, I'm not suggesting a substitution. I'm trying to figure out a better way of keeping it straight it in my mind.
Not exactly. A more literal translation is more like *A cute sister, yours."
I keep making the same mistake with the translation by typing "Your sister is cute, " Kiuke kou kaikuahine.