My favorites, pretty much in order (this keeps changing), are:
Ceridwen Mimosa or Ceridwen Sylphide
Hespera Windermere or Hespera Shalott
Myristica Tempest or Myristica Chione
Elbereth Ren or Elbereth Clio
Tinuviel Cyrene or Tinuviel Elaine
Admittedly idiosyncratic reasoning: Whenever possible, I tried to pair complexity with comparative accessibility, if not in meaning, then by sound. Along the way, I came to understand that even though there are some "word" names I like, it seems I prefer the relative "veiling" of names whose meanings are shrouded in allusion, history, other language bases, or literature. Thus I eliminated Seawillow and Winterose; I eliminated Lorien because it sounds/reads male to me. Niniane I eliminated because too much of a tongue twister, even on this list. Nienna reminds me of Sienna, Evelake could become Evie and we're swamped with Evies. Everild? Somehow, mixed with Emerald in my mind, cannot make up my mind about the "ild" ending, but this one very nearly made the top five.
Winterose, Rhiannon, Genoveva, Evelake, Hespera, Ceridwen, Belphoebe and Altalune are my favourites and the most usable.
I don't mean this to sound but I did have a little giggle at Seawillow, it just doesn't look like a name and makes me think of sea lions. I couldn't ever imagine having a child in one of my classes named Seawillow, sorry.
Eilonwy looks like a jumble of letters rather than a name, and pronunciation will be an issue.
Lorien looks masculine to me, while Myristica seems a little like you've tried to go for the work Mystic/Mystery and it seems a little cheap and I don't say this to offend just the impression I'd get if I saw it on a class list.
Nienna isn't too bad, and neither is Finvola, Illyria (if I'm saying it right) and Niniane.
Altalune Pelagia Ren
Altalune Mimosa Clio
Altalune Clio Tempest
Belphoebe Arcadia Shalott
Belphoebe Tinkersnow Ren
Belphoebe Endellion Cyrene
Belphoebe Ludmila Tempest
Ceridwen Finvola Meadowsweet
Ceridwen Hespera Tempest
Ceridwen Stellaluna Shalott
Genoveva Pelagia Tempest
Genoveva Endellion Fairlight
Genoveva Tempest Alcyone
Hespera Meadowsweet Chione
Hespera Clio Sylphide
Hespera Moonbeam Clio
Hespera Villanelle Evenstar
Rhiannon Mimosa Belisande
Rhiannon Tinkersnow Fairlight
Rhiannon Windemere Cyrene
Rhiannon Illyra Moonbeam