Translators generally specialize in particular fields for that very reason - you can't translate something that you don't understand well. The more specialized the topic is the more important that becomes.
If I'm translating a medical text, it is important that I can actually understand what the text is saying, or else it's pretty easy to run into problems with the translated text. That's why you often see medical translation done by people who are actually medical doctors.
Then you have to consider whether or not the translators have altered the text for (often quite reasonable) reasons of their own. Take the Takemusu Edition of Budo translation - the translation is clearly altered, with "ki energy" substituted for "strength".
Absolutely. I am aware of these issues, having been brought up in translating the Greek and Latin Classics. You have to establish the text first and then go on from there.