I think the main point's just that there's no real reason to keep the JP text legible if it comes at the price of English readability. Ex:
Middle is a lasso+content-aware fill (a photoshop thing you might not have access to), right side is just blurring the JP text so it doesn't interfere with the english text.
Even if you don't have a redrawer, usually lazy smudging like this to reuse the existing text's space is better, because it gives you area to have actual legible text. Better to have some unclean pages that can be read than pristine raws + tiny text.