Original sentence: The word "duty" was not in the codebook, and was not substituted as "confides" had been (the two closest words "best" and "utmost" were not deemed appropriate), so had to be spelt out, meaning the whole message required twelve "lifts"
Edited sentence: The word "duty" was not in the codebook, and was not substituted as "confides" had been so had to be spelt out, meaning the whole message required twelve "lifts"