I've known 2. On would be 19 now and one about 60.
One spelt Keren and one spelt Keryn. I've not seen the name spelled as you have.
I do think they would have to spell if for people at first, but it is easy enough to then remember. I'd only see it the same as having to spell Jane or Jayne, as both are equally 'right', and easy to remember once you know how the name is spelt for that particular person. It isn't really weirdly spelt.
I quite like it as a name. Nice sound to it and easy to know how to say it if you see it written down.