Cariad Mwyn? That would mean something like 'gentle sweetheart', perhaps that's a bit wet... you'd need to check it with a proper Welsh speaker too. But it sounds quite nice - mwyn pronounced 'moyn', more or less.
I'd avoid Calon Lan, that's the name of a popular hymn - a very nice one, but may lead people to expect a choir or something.
You do want to make sure that it's not too mystifying and unpronouncable, or you'll be working against yourselves...