Does the "perfect translation" exist? In my opinion, no. There is no such thing as a perfect translation, but before trying to explain my reasoning on this, let's introduce the linguistics term "Anisomorphism".
Anisomorphism: (linguistics, lexicography) The absence of an exact correspondence between words etc. in two different languages; the differences between two given languages that create mismatches in a translation dictionary.
What this means is that there are certain words or expressions in a language that can't be "perfectly" translated into another one, only adequately. For instance, let's take the Welsh word Cwtch, which meaning is the type of hug that makes you feel like you are safe. The type of hug that the person you trust gives you when you feel scared, sad or in danger, and that makes you feel like everything will be all right.
Let's suppose for a moment that Cwtch was a regular verb and we had this short paragraph:
"My world was shattered, but the moment he cwtched me, I suddenly felt better. I knew, right then, it was going to be ok."
How would you replace cwtched? Just "hugged," or you'd rather rephrase it into four or five words? Probably we could come up with a whole set of variations and we'd still feel that our translation has lost something in the process. Maybe right now you could think of other times when you were trying to explain your feelings or an event you experienced, and you couldn't find the right words to express exactly what you wanted. Translating your feeling into words becomes impossible. So we can ask ourselves again: Does such a thing as a "perfect translation" exist?
When thinking about translations, we should go one step further than just Spanish, English, and Chinese. We have to think about programming languages such as Python, Ruby and C++, about symbolic languages such as maritime signal flags, and signed languages such as the ASL (American Sign Language).
If you are a programmer, how many times have you heard, "X is a better language than Y because you can directly write this, and do that."? Doesn't that mean that what you want is translated easier into, say, Python?
How many times have you gotten into an argument because what you said was missinterpreted? Because you couldn't express your feelings accurately?
Languages are imperfect, they are a bunch of made up words to convey an idea, and, in my opinion, that makes the idea of "a perfect translation" impossible. Each person will interpret your words their own way, and depending on their understanding they are going to translate it a different way. Culture, knowledge and tools available will make this interpretation process easier, but ultimately, the translation will be an approximation of the original idea.
So, there you have it. The perfect translation doesn't exist. This doesn't necessarily mean one translation will be better than the other one, it all just means the translator might have chosen a different approach to convey the same idea. It will be up to you to choose which one you prefer.