I am not good with genetics and colorings, but there are lots of people quite good at it right here on the forum. Hopefully they will be able to help you. Your birds sound beautiful- maybe you could post pictures?
Lutino doesn't eliminate melanin pigment (it just messes it up really badly) but emerald DOES have an effect on the distribution of melanin. So you might get different intensities of yellow in a lutino emerald, just like you do in a lutino pearl.
There probably aren't very many of them. Emerald/olive is rare to begin with, and it's not desirable to mix it with mutations that would make it hard to see the coloring. Lutino will definitely make it harder to see the emerald! But the common mutations are so widespread that it can be hard to keep them out of the bloodlines for the rare mutations.