I'd eliminate these as a sister to Romilly:
Agnes, Eugenia/Eugenie,
Hebe,
Harriet,
Hedwig,
Penelope, Thisbe,
Sybil,
Winifred --Too ugly/harsh/clunky.
Bronwen,
Camille,
Cecily,
Cosima,
Ianthe, Eulalia/Eulalie,
Hermione,
Linnea,
Marina,
Olympia --Too similar in sound.
Alexandrine,
Arabella,
Araminta,
Eleanora,
Georgiana --Too frilly.
Gwen,
May,
Nora --Too insubstantial.
Edith,
Gaia,
Hero,
Katharine,
Keturah,
Milena,
Miriam,
Ophelia,
Tempest,
Wilhelmina,
Wren,
Zelda --Jarringly different styles next to Romilly.
Philomena,
Guinevere --These push Romilly into pretentious/over-the-top territory.
These sound great with Romilly:
AnastasiaElizaFlorenceFrancesHelenaIsadoraKerensaMargotMargueritePhilippaVivienne
I could take or leave the rest.