Although I have no experience with the standard that you mention, our company has acquired translations for other GB codes (mostly construction) and they are usable, but not great.
Most of the translation is good, but subtle technical terms are sometimes missed or translated incorrectly. For example, in GB 50009, the building loads code, where the original text intends to refer to "cladding components", it instead is translated as "enclosure structures". This could easily result in errors unless the person reading the translation is very familiar with what should be expected from the text. Even then, we often must go back to a native speaker to clarify from the original Chinese version of the documents.