The raped-by-a-swan thing is... off-putting? Nope, doesn't really cover it. And that's my only association with the name, so no, don't fancy it with any pronunciation. (And I expect you'd need an accent to get 'lay', as most English speakers would probably rhyme it with
Freda)
Re Letha: Lisa-with-a-speech-impediment made me grin. Tis true though.
Do you like
Lída?