Etna is new to me as a name, however I like it, and I like how there are intuitive nicknames "
Ettie,
Etta". I don't think it would be strange, considering all of the other random things people are named after these days.
I like the idea of
Etna Florence. Of yours, my favourites are
Etna Celestine,
Etna Irene, and
Etna Beatrice.