Back when I studied translation, one of our teachers told us that corpus research has shown that translated texts tend to have more synonyms for words than original language texts. Most translators know this. Translators have a natural tendency to add more variety to a text. If the same word appears several times in a text, the translation of that text will probably have two or more synonyms for the word. Whether or not this is the right thing to do depends on the text, and the type of text. Sometimes, the repetitiveness grates on our ears. One argument against the practice of adding variety is that the reptitivity merely mirrors that of the source text. A translator spends a lot more time with the text than most readers would, and perhaps the repetitions of the target text end up bothering him more than they would bother a reader. A few months ago I translated a text where the client explicitly asked to undo the variety since it concerned a term of art. In this particular case the subject actually was art. A term of art, as defined by Merriam-Webster, is a word, or a phrase, that has a specialized and particular meaning within a particular field or profession. The text discussed at length artworks exhibited at various venues. At some point I begun alternating between "exhibited" and "displayed". In an editing session with the client, he explained that this was a specialized term, and should always be "exhibited". It was a very productive editing session, where the client raised issues he had with the translation, some places where he felt his intention did not get through, and I rephrased it to match his intent, and some places where I explained why my phrasing was appropriate, given my knowledge of the target language and culture. Editing goes much better when it's conducted as a dialog. While I accepted the client's request to keep the term translated consistently. I felt it was repeated too much in the text, and in a few places suggested rephrasings that would eliminate some repetition, without substituting a less professional term for it.
I had a similar experience with a translation of a text about music, where initially the client marked quite a few places as "issues." Some of the "issues" turned out to be preferences than actual mistakes. The client had the better of the domain, so while I did point out that these shouldn't counted as "issues", I accepted her preferences. In other places, where she wasn't happy with the language, I suggested a couple of alternatives. That editing session was conducted as an email correspondence, which started on the stormy side, but quickly evolved into a cooperative discussion.
Editing a translation as a dialog works better than editing as a confrontation. Not all changes made by the editor (which is usually not the client) have the same weight and the same effect on the text. I don't feel that I need to defend every word I wrote. Sometimes I do assert myself when the changes are clearly detrimental to the message (even if I'm discussing it with the author, or a subject expert). I'm always prepared to explain my choices. One earns respect by being professional and treating others with respect.