A form/variant of a name doesn't have to sound exactly like the one it derived from. In Hawaii, their traditional alphabet, I believe, did not have S, R or H in it. I could be wrong.
The Hawaiian alphabet only has 12 letters: a, e, i, o, u, h, k, l, m, n, p, and w. So, there is no S, R, or H, and thus, of COURSE this doesn't SOUND like Sarah. It's the Hawaiian form.
When translating my name (Emma Starr) to Hawaiian, I got the name Ema Kala. When I translated my mother's name (Sara) it was also Kala. How can it be both, plus other names that begin with S? (Translated on an internet translator, so don't call me stupid or anything. If it's wrong, it's NOT my fault.)
Either way, I think it's gorgeous and were I ever to move to Hawaii to raise a family, I'd name my daughter this.