It might be good if you wanted to call her Mac (or had a cough:) But it wouldn't work in Welsh. The old-school female version would be Macsena, which I've never seen, but a lot of Welsh-speakers don't like the -a feminine endings 'cos they're borrowed from English, and the -i ending is more 'authentically Welsh', so that's probably why they went with it.
I am clearly a terrible Welshwoman because I actually quite like Macsena. :/