Sorry - both of those open your baby up to my pet-hate - mummy or daddy choosing names they like rather than ones that will be good for the baby.
Tesni? Tala? Ffion? Please, please, please, tell me you are kidding and you are not actually seriusly considering lumbering your baby with any of these names. I have grown up with a non-traditional spelling (Saara, rather than Sarah) and trust me, I would have given anything at school age to have a 'normal' name. And mine was only a different spelling to a very tradional name in my own country - I hate to think what it'd be like for a child called 'Ffion' or 'Tala'. I know I certainly would not touch a name such as that with a barge-pole. I think to do so is tantamount to child-abuse.