I suppose it's because I'm not used to it, but when I looked at it I just saw 'lean' as in 'skinny'. Which meant that I heard it like that in my head; leenora, like
Lee +
Nora. But I suppose you wanted it to be like
Leah +
Nora?
I don't think the
Leo- bit sounds masculine anyway. The name
Leo has a definite O sound, but the first O in
Leonora is a schwa. So maybe it looks masculine? But hearing it would be more frequent than seeing it, surely?
I can't be bothered to look it up right now - past my bed time - but I think
Tennyson wrote a poem, probably one of his more medievalist ones, about someone called
Eleänor, so clearly he intended it to have four syllables. I remember being cross because the name only appeared on a line by itself as a refrain, so it wasn't clear where the stress(es) would fall.