I work with languages, but I hated most of my English classes in high school and beyond. The literature classes were Ok. The grammar classes on the other hand … It always seemed to me that the grammar of English was a lot more slippery and complicated than my English teachers let on. My linguistics studies confirmed me in that opinion.
One definition of grammar is: “A propriety of speech.” Someone suggested that grammar is not a property of speech but rather an impropriety of speech. It is so hard to get your hands on it. There are rules, but also so many exceptions.
A game with rules like English grammar might be considered fixed by the Gaming Commission! This is not just true of English, but of all living languages. Many African languages are not written, but they have complicated grammar all the same. Just ask the missionaries who learn them, or the translators who attempt to describe them. I asked one translator about the number of genders in the language he was working on. He said that he stopped counting at around 120.
One translator was reading a draft translation to people to see if it communicated clearly. They came to a part that said: “Don’t steal from widows”, and everybody laughed. It turned out that the way it was said implied that one should steal from other people than widows! It sounded like “Don’t steal from widows; steal from someone else instead!” To get the right meaning meant using a grammatical structure in that language called topic-comment. In topic-comment, the topic of the sentence is stated first (widows), then the thing one wants to say about the topic (don’t steal from them). In that structure, the verse read “Widows, don’t steal from them.” This communicated clearly and avoided the idea that it is okay to steal from other people.
All translators, even those translating into their own language, need an explicit knowledge of the grammar of their language, or they might not use features like topic-comment even where they are necessary to be faithful to the meaning. So even translators translating into their own language need training.