The subject being discussed is art, and art writers use their own unique style of writing. But it is a perfectly good and well formed sentence. A) makes it difficult simply to interpret one element, an image, in terms of another, its reporting in words. B) makes it difficult simply to interpret one element, [first part means one ELEMENT of the artwork any element of this the particular artwork being reported upon] C) an image, in terms of another, [second and third part means any image of this style type of art] D) its reporting in words. [Fourth and final part of the part you are enquiring about means, to report in words to write about. It is difficult, simply = simply is a common way to emphasis what is said. The entire text is a little ambiguous because you have to remember for such a long amount of time, that the text began with "there are artists" = therefore many, more than one image of this style/type/class/classification. Then by the time your mind has reached the end of the text, it is saying. "one element, an image," giving the impression of only one singular Image, "the image being discussed", but the text is discussing all such images as well as this one particular image. For a learner to be confused because they may have picked up on this point, shows the learner may be not a learner after all but very accurate with their observations. If any learner has noticed this ambiguity then congratulations and well done, you deserve the class prize.

That is a very confusing phrase so I can see why you are wondering about it. I think you and I are thinking about it in the same way. I would re-write the phrase like this: "...makes it difficult to simply interpret one element or image, individually or in terms of each other, by only using words."