I like your list of Classically-influenced names but many on MN will consider them too try hard, as they would my kids' names too.
But where we live they fit in well.
Specifically on your list:
Iris I love. It's not as usual as your others though, I know several under 3.
Appoline is the most unusual of your list - I've never heard of one. I'd personally rule it out on apple-y nickname grounds.
I know a few Cressidas of a mixture of ages and the problem is always nicknames. They all seem to sometimes get Cressie, and dislike it. If you don't mind it then go for it.
I prefer Celestine or Celeste to Celestina. The -tina almost overwhelms the prettier first two syllables.
Serena I'm biased against from knowing a not very nice one. But objectively it's fine.
I wonder if you might also like Seraphina, Delphine or Delphie, Athena or Daphne.