The Proofread tab reads the edition's newest manuscript and lists the words its dictionary doesn't know and what's written more than one way, with the words around each place and a link that opens the editor there. Nothing in the manuscript changes until you change it.
Spelling: each word the dictionary doesn't know, how often the book uses it, and the dictionary's suggestions. Names are left out: a word capitalised in the middle of sentences, and the names in the book's story bible. So are passages you marked as another language and words in capitals. A word that's right as it is ("Not a mistake") stays on the edition's own list and is left out from then on; take it off the list again any time. English is checked with both the American and the British dictionary, and Portuguese with Portugal's and Brazil's, so a word either knows is right. Polish, Ukrainian, Russian, French and Spanish have their own; German and Italian aren't checked yet, as their dictionaries' licences don't let the studio include them, nor are languages written without spaces, such as Japanese.
Names: a name the book uses often, and a rarer word a letter away from it: "Mara" in most chapters and "Marra" in one. Names of eight letters or more are compared two letters apart. A word counts as a name when it's capitalised in the middle of sentences and seldom written in lower case, so a word like "hope" isn't taken for a name. The names in the book's story bible count however rarely the book uses them.
Terms: a word written both with a hyphen and closed up, such as "e-mail" and "email". A hyphen against a space ("well-known" and "well known") is left alone, since both are right in their places.
In languages whose words change their endings (Polish, Ukrainian, German and others), only a difference before a name's last two letters counts, so the name's own endings are never taken for typos. German capitalises every noun, so there only the story bible's names are compared. Languages written without spaces between words, such as Japanese and Chinese, aren't checked yet.