The post name is ILANA, not a Welsh name. The Welsh name which she proposes is Claerwen. It is a place name (a river in Powys) used as first name in Wales (an example is Claerwen James); it comes from the Brythonic roots claer, "bright", and gwen, "white, fair, holy". Since the place name ends in (g)wen, the name is used as feminine name.
Here you have a link to the only reliable online source in Welsh names that I know: