- In general, it's a common problem for anime and manga fan subs to intentionally leave certain words untranslated, either due to a misconception that they have a stronger connotation in the original language than they really do (such as "Nakama") or just plain carelessness (Translator's Note: "keikaku" means "plan"). Or just because the fansubbers are pandering to hardcore anime fans and assume they're familiar with the meaning of, say, "baka", and/or because, for them, these words sound cooler when said in Japanese.
- A case of this trope with manga scanlations is transliterating but not translating Written Sound Effects. This is in part because, to a non-native speaker, Japanese sound effects can look ridiculous and sound nothing like the actual sound (although it's not like English sound effects are that much closer); but a large factor in this is certainly the sheer number of Unsound Effects that are commonly used in Japanese (see that trope page for more), including things like しーーん "shiiin" for Visible Silence.
Analysis / "El Niño" Is Spanish for "The Niño"