I wrote an entirely wrong word spelled entirely correctly.

Wikipedia has this to say about typos:

A typographical error (often shortened to typo), also called misprint, is a mistake (such as a spelling mistake)[1] made in the typing of printed (or electronic) material. Historically, this referred to mistakes in manual type-setting (typography). The term includes errors due to mechanical failure or slips of the hand or finger,[2] but excludes errors of ignorance, such as spelling errors, or the flip-flopping of words such as "than" and "then". Before the arrival of printing, the "copyist's mistake" or "scribal error" was the equivalent for manuscripts. Most typos involve simple duplication, omission, transposition, or substitution of a small number of characters. (emphasis mine)

https://en.wikipedia.org/wiki/Typographical_error

Hmmm. Definitely spending way too much energy here.

Your quote mentions "scribal error". Your spelling part of the brain knew what it wanted to write. The writing part inserted a different word. Now my lack of knowledge of brain parts is an error of ignorance, so 'spelling part of the brain' isn't a typo.