Crescentia Edith Ludwig

she keeps a diary, written entirely in a latin-adjacent language she made herself

Her creator taught it and English to her!! He wanted a child but couldn't connect to any woman he met, so he made one himself. Realizing robots can't age, he modeled her to always be in young adulthood (~22) but raised her from a child-like state. Now she is about 45 years old. It was a bit of a weird situation, but her creator tried his best and thought it would be unfortunate for her if she was always a child or child-like in appearance, because he didn't want people to look down on her as a person or underestimate her mental or emotional maturity once she was properly old enough.

She is 4'11.

she keeps all her secrets in her diary!! someone with a good knowledge of either latin or google translate could probably piece together context clues for it

as a nickname I think she could go by tia probably :3c

I think she also has a passion for piano but feels great sadness

has abandonment issues.... she doesn't often feel like she truly has a presence or is a person with real feelings

she tries to compose music to touch people's hearts and show she's 'real' but doesn't feel like her own music is anything more than hollow due to performing for a faceless audience or disinterested family, throwing her into a cycle of despair, though her original creator always supported her endeavors and journey to free will. The rest of the family considered her more of a maid robot to do chores.

she doesn't even want to fit in, she just wants to feel like she's a person who exists and could be listened to or cared about, even if or when she dies. Her creator died so she assumes she will someday too, but she wants to be appreciated on this plane of existence.

She enjoys learning!! Anything you teach her will be appreciated greatly. There are a lot of things she doesn't entirely understand, but she's eager to study.

The gears on her head rotate with every movement of her head/neck. 

Theme Idea hehe