All aspects of translation, including the treatment of proper or made-up names, are the decision of the translator.
Firstly, as you correctly stated, the author cannot be expected to know the target language and to be able to give any insights on the subject.
Secondly, the treatment of names is only one of the many decisions that the translator must take. These decisions are a part of the general strategy that the translator chooses (for example, to what extent to adapt the text to the target culture, how to handle the cultural expectations of the target audience, and so on).
Granted, it can happen that a translator consults with the author or asks their opinion, but that is absolutely not a standard and depends on the translator's and author's position, the stance of the publishing house, and so on.
 An exception here are special conditions set up by the publishing house. For example, if a text belongs to an existing franchise (say, a Star Wars novel), the translator may be required by the publishing house to stick to an existing terminology.
 There are exceptions, of course. For example, J. R. R. Tolkien expressed his opinions about how proper names in his work should be translated in Guide to the Names in The Lord of the Rings. However, that was not binding for translators, and there are existing versions where the translator decided to ignore these suggestions. Of course, the case here is a rare one, as Tolkien was a linguist and constructed languages played an important role in his books.