Because Japanese and English aren’t related languages.
European and Indo-European Language can be much more easily translated with each other because they share root forms. Japanese and English do not.
Hence translations are adaptations.
The honorific not changing is considered correct in English btw. You should keep Monsieur or Frauline too. We just do that less these days because formality in the West is just about dead. In Japan it isn’t politeness/formality is invested in the language at deep levels.
Line 1. It happens all the time TBH. But I rarely buy books without reading the first few pages. So I haven’t got stung very often.