A: Finding and replacing the malapropisms within the text. They’re more difficult to spot than other errors because usually it is a real word sitting in the place of the correct word choice. Spellcheck won’t find it. Many readers will also skip over the malapropisms without seeing them, either because they don’t know better, or they do, and their mind replaced the word with the correct word instantly as they read the passage. Even after editing the book, I would still find malapropisms.
For example in the original text of Zaria Fierce and the Secret of Gloomwood Forest one of the characters said to another, “So we’re at a bypass then?” The real word is impasse (the point where progress is halted due to disagreements, lack of comprise, and physical barriers), not bypass (a road around a place, a reroute or detour to avoid something). As you can see, the words have two very different meanings and the sentence meaning changes depending on which one is used. The contextual clues would allow you to deduce what I really meant as the author, but it’s far better if I fix the malapropisms before you get your hands on the book. 🙂