Ceredig is super rare! - great sighting. The original was a 5th-century king; he's got a county named after him, Ceredigion.
Yup,
Anni is a common Welsh version of
Annie. I've seen Ani, too - and Liwsi and Betsi and Nansi and
Mali (
Molly) and Magi, and probably a few more I'm forgetting.