Readers of The Goblet of Fire come across several books of magic targeted at specific readers. One of these is Basic Hexes for the Busy and Vexed, which is aimed at busy or vexed wizards. Presumably it is aimed at wizards who don't have the time to spend on elaborate traditional spells that require a lot of preparation and effort. The title echoes more mundane book names like Basic Recipes for Those On The Go .
The Chinese translator translates this title as 对付多动和烦躁动物的基本魔咒 Duìfú duōdòng hé fánzào dòngwù de jīběn mózhòu, meaning Spells for dealing with restless and fidgety animals. The mystery here is how she managed to arrive at such an interpretation.
The keys to the problem are:
(1) The meaning of the preposition 'for'
(2) The meaning of 'the busy and vexed'
(1) 'For': Anyone from an English-speaking background can see that 'for' here means for the benefit of those who are busy and vexed. But this knowledge is derived from exposure to all kinds of language in everyday life. Most English speakers would be hard put to explain exactly what the difference is between this 'for' and the 'for' in Basic Recipes for Cakes and Pastries -- a book for making cakes and recipes.
It is not surprising that the Chinese translator comes up with a book for dealing with 'the busy and vexed'.
(2) The expression 'the busy and vexed' implicitly means 'busy and vexed people'. Again, this is obvious to a native speaker of English but is not clear from a surperficial reading because it isn't actually spelt out. Since the Chinese translator has already misinterpreted 'for' as meaning 'to deal with' rather than 'for the benefit of', she has already gone some way in the wrong direction.
Dictionary definitions don't help that much, because both 'busy' and 'vexed' have a range of meanings that could apply to all kinds of situations. Why couldn't 'the busy and vexed' be interpreted as referring to 'restless and agitated animals'?
Eventually, the creative imagination of the translator came up with an interpretation that seemed to fit: Spells for dealing with restless and fidgety animals.
This mistake points up the need for real-world experience in English in order to be a good translator. While I do not personally know the translator and there are obvious dangers in generalising, it is still the case with many scholars of English in China that their book knowledge is much superior to their grasp of English as actually used in English-speaking countries.