Elko, Luèn, Etta, Uma, Pilar, Edie, Elma or Muriel

What special names! I wouldn't personally choose them because I think a child has to say their name so many times before it's clear. And let's not even talk about spelling it.

I think Uma and Edie are the best (pronounced in English).

Elko and Luèn sound more like boy names to me.
Etta: I immediately think of Etta James and the song At Last.
Pilar: special, beautiful for Spain, but I wouldn't use it in the Netherlands because it quickly becomes pilaar, I think.
Elma: not my thing.
Muriel: not beautiful.

Viènn I find really lovely! Maybe an idea?

I'd go with Uma, Luen, Pilar, or Muriel.
Edie and Elko feel too much like Eddie and Eelko to me. The others don't look as nice.
Besides, I know a Pilar, so it doesn't sound that strange to me. I think Muriel and Luen are the prettiest.

I think Pilar and Muriel are beautiful, the rest not so much.