There are many hurdles to creating an accurate translation of Sun Tzu's The Art of War. Many of these hurdles are unique.
First, ancient Chinese is a conceptual language, not a spoken language. This means that its characters cannot be properly understood as verbs, nouns, adjectives, adverbs, and so on, as can words in other written languages. Ancient Chinese characters represent general concepts that can be translated in an extremely wide variety of ways.
While we start with a given set of characters making up Sun Tzu's The Art of War, there is still a serious question about what each of those characters means, or rather, what each character meant in Sun Tzu's era. As would be expected over long periods of time, the meaning of specific Chinese characters has shifted. Some of the most frequent mistakes in translation arise from the reversal of meaning from semantic drift.
Sun Tzu took a very scientific approach to his work. He carefully defined his terms throughout. In one sense, the entire work might be considered a definition of conceptual ideas and the formal relationships among those concepts. Unfortunately, most translators pay much less attention to Sun Tzu's definitions than the Chinese dictionary's.
The final reason that translation is difficult is that the text was written in a kind of code. Much of Sun Tzu's writing refers to a scientific system of diagrams and analogies used by the Chinese in classical science. Just as modern poetry uses metaphors, ancient Chinese relied upon the many connections in this system to express complicated ideas without having to explain them in detail. No translator was aware of this system until Gary Gagliardi's lectures and research revealed it. Now it is recognized around the world.