Could you help me to explain the following paragraph?
No doubt the reason there "circular" sentences turn up in draft translations is that often there is nothing in the Chinese to indicate the logical relation between the two parts of the sentence. With no clear guidance from the original, the translator is obliged to insert a conjunction on his or her own —— “and” or "in order to" (sometimes even "or"). Unfortunately, none of these can solve the basic problem, which is the double statement itself.

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Firstly, what are "these circular sentences' referring to? You have to read the text that comes before in order to understand this.

Anyway, this is how I understand it.
In Chinese the relationship of clauses and sentences is sometimes given by their order, and there is no specific word indicating the relationship. So if someone is translating it quickly, or doing a draft, he is probably using machine translation, then has to fill in a conjunction. 
In my opinion, I don't think this is a problem of the language. I think the problem lies in the fact that the translators aren't very good.