Where to find her
You will find Sylvia in her cave, Shadow’s Whisper Cave in the central part of Hernand, north of the city.
Additional Info
Since she is only a novice witch, she is capable of the very basics like adding or extracting Abyss Gears for you or unlocking an Abyss Gear socket, but she will not be able to craft or synthesize Abyss Gears for you, nor does she have a workshop to sell things.
You can actually purchase a few items that you find around her, like the Bright Yellow Dye, sitting on a small table behind Sylvia.
