Faenorn is looking awfully close to Fëanor, unfortunately.....
It's tough to use a very limited word list and then say, '... make the names sound different, but not
too different...'
I do like elms, though! One of my favorite types of trees. And Treebeard looks vaguely elm-like (elms are rather ent-like trees), so the Green Elf-Ent association works there, too.
Enelalmas = Between elms
Okay, okay, I'll put that idea aside!
'Silver elm' would be fine. Telfalm? Almtelf? Hmmmm, maybe something from the root
MIZD would sound better. I know that
meord is a noun, not an adjective, and is more of the 'wet' side than the 'grey' side of that word. But
Meordalm sounds much nicer than
Telfalm. Not sure how to get the Nandorin version of 'mith'. Almith sounds okay, but more like it should be a town in Massachusetts, not an elf in Ossiriand.
PS: I too like Fenelind and could live with that! The Green Elves call themselves Lindar/Lindi, correct? So, a nice echo. Also, three syllables makes it sound like it's in the same family as Celeborn (I don't like 5 syllable names very often!)
PPS: alm=elm in Nandorin is one of the words Tolkien did record, so I see no need to change it to a neo-Nandorin form (even if David Salo did create a much more extensive vocabulary to play with!)
Ardalambion's Nandorin word list:
https://folk.uib.no/hnohf/nandorin.htm
Eldalmo's Nandorin words/names:
https://www.eldamo.org/content/language-pages/lang-nan.html
https://www.eldamo.org/content/language-pages/lang-dan.html