The author wrote,"Because there is a vast interval between “good” and “bad,” it accommodates complex relationships." which, to me, shows they don't truly grasp the cultural context of his Chinese environment. There is the same interval between good and bad in both Chinese and Western values and thinking and terminology. What makes it seem there is a difference is the hesitancy to be affirmative in Chinese culture. To affirm some thing is to claim knowledge and expertise, and in doing _that_ comes an expectation that those around the Affirmer acquiesce to their expertise. This is another facet of Face. Very few people will claim such a level of knowledge and expertise and experience, so the words used are purposely "vague". It's not a issue with the terms.
I was once asked if I speak Chinese and I answered affirmatively, "Shi da" (very bad pinyin btw). Everyone thought that was hilarious! They were able to think it hilarious because, at the time, I was just a young single man, and my answer made it sound like I was affirming that I speak Chinese, _all of it_! But in my mind the conversation was in Chinese, I understood the question and gave an answer in Chinese, so of course I can speak it...just not fluently. I learned from that experience that a better answer is, "keyi", which is essentially "enough" but in a more humble mode and the breadth of that word itself is adapted to the context. If asked in a market about my Chinese, "keyi" means "enough to do shopping" with no claim to more than that. If in the context of a class at university, it meant "enough to do the work" but not claiming to be super smart, NOR, dumb (since it's at university). It isn't the words, it's the interpersonal culture, face, and both communicating and showing you know where you fit in.