Re: Gladys, the genuine Irish name...
My grandmother worked with a female Clarence. I never met her, so I never got the chance to ask her how her parents came up with her name. My grandmother--a woman who was absolutely not a name nerd--wouldn't ask for me. I was so curious!
I've never met a female Shawn irl, but there is singer-songwriter Shawn Colvin. I think it's her real name, not just a stage name. I don't see it as a female name, though. It's just a phonetic spelling of Sean used on a girl. I've met more than one Shawna.
I know two female Austins, one spelled Austyn and the other spelled Austen, after Jane.