A relevant term here is translationese. A translated text tries to both respect the original work and the new language. Both of these can not be true at the same time, so there is a varying amount of trade-offs.
I am drawing from the article
Vered Volansky, Noam Ordan, Shuly Wintner, On the features of translationese, Literary and Linguistic Computing, Volume 30, Issue 1, April 2015, Pages 98–118, https://doi.org/10.1093/llc/fqt031 , open access http://cs.haifa.ac.il/~shuly/publications/vered.pdf
There is study on the universal features of translated texts.
Quoting the article above:
Baker (1993) calls for compiling and digitizing ‘comparable corpora’ and using them to study ‘translation universals’, such as simplification, the tendency to make the source text simpler lexically, syntactically, etc, or explicitation, the tendency to render implicit utterances in the original more explicit in the translation. This call sparked a long-lasting quest for translation universals, and several works test such hypotheses in many target languages, including English, Finnish, Hungarian, Italian, and Swedish (Mauranen and Kujamäki, 2004; Mauranen, 2008).
I recommend reading the second section in the article for more information and further references.
You might also want to check if some more recent publications discuss Chinese in particular; the articles citing the one above are a good first step: https://scholar.google.no/scholar?cites=2869890259940137865
A search for "translationese Chinese" might yield more results: https://scholar.google.no/scholar?q=translationese+chinese
Some general trends seem to be that translated text tends to be simpler, to use less structures and vocabulary particular to Chinese but missing from English, and to contain more vocabulary and structures shared between Chinese and English. The translated text is presumably more explicit than original text would be.
All in all, I would assume that reading the translated text is easier than reading an original text. However, depending on your mastery of Chinese, this might not be a problem. If you are not yet fluent, you are likely to learn a lot anyways. If your eventual goal is to be able to write native-like Chinese text that natives consider beautiful, and you are already at a high level of mastery, then considering reading original Chinese literature instead, just like a Chinese person should do.
Also, you could ask a native Chinese if the language in the book is okay. If the translation is good, then, supposing you are not at very high level of Chinese, the difference in learning might very well be small. This is based on a pure hunch. Please investigate the literature above to verify or falsify; maybe someone has looked into it.