I doubt most people are aware of the
Electra complex; I think the unpopularity of this name is due to the fact that they both sound like elaborations of words: electric, elect, letter. Also
Electra became a comic book character so the name has a (slightly silly, sexualized) pop culture association that is maybe not doing it any favours.
I don't mind them, I think
Electra is badass and I would use it BUT I would be fully aware of what I'm dealing with there.
Elettra is a bit weird to me, it's exotic but a tad off-putting as well. I like it ok, seeing it is fine, but I would never use it.