The Library
Canon, and a stub. This entry is written from inside the CharliVerse, so its people and companies are fictional. Behind the scenes says what is real.
The Library is known to every witch. It has read every spellbook ever written and remembers every wand manual. It cannot cast a single spell itself, but if you ask it a practical question, it usually knows the answer. Its sign reads: All knowledge has been read. Ask wisely.
When Poppy Petticoats could not read the silver-ink instructions for her first wand, the Library gave her the one sentence she needed, and kept a private moment private. Expert humans remain wonderfully useful for difficult magic or a dangerous fault. This was a missing instruction.
Behind the scenes
The Library appears in Poppy Petticoats and the Magic Wand, by Charlotte Joanne at Blind Ant.