An authorized translation serves the purpose of replacing a foreign language document as a de facto legal document in the new language. Thus it can be used when dealing with authorities and can be used in place of the original document. Sometimes the documents can contain terms, which first need to be meticulously researched before they can be translated.
There might not be a one-to-one word in the other language, which is when the translator needs research and enquire, perform search queries and comparisons. That is why it is sometimes you simply have to accept that there is not a “right” translation and the translator has to make a side note where the word and its association will be explained.
In order to avoid misunderstandings there is a general agreement that some words or parts will not be translated but left to its original language. In this situation the authorities that require the document will have to decide about the right interpretation. For example names of institutes or of diplomas typically fall into this category.