&gt;A guy who is 100% fluent in source and 99% fluent in target will produce a perfectly clear but very slightly stilted translation,because he&#x27;s not aware of the few mistakes that he makes.<p>Why isn&#x27;t the reverse true? It is only that the lossyness of the conversion process is invisible in the result, so somebody reading it would not know that it&#x27;s wrong, it still produces the same quality of translation i.e. that its not perfect (or as good as can be).<p>Additionally, there are so many words in english that it&#x27;s not possible to know them all, and so one has to assume that all people are at most 99%. But my english alarm doesnt go off everytime a word like &#x27;mellifluous&#x27; isn&#x27;t used. So I even doubt the claim that a guy who is 99% in the target language will make a &#x27;stilted&#x27; translation. There exists a skill level where a person can produce a text that won&#x27;t read as &#x27;wrong&#x27; but won&#x27;t be as good as it could possibly be and this skill level is sufficient to not have a text feel stilted. Not to mention most people do not have the same writing skills, and a very good high school student writer writes a much more pleasing text than his schoolmate who is not very good.