Re: Just a quick question.
"Nobody knows a foreign language well enough to do a proper translation, except trained professional translators."
That's a slight misconception. Even if you don't speak a language well, you can produce decent translations with enough research, looking up every word in a dictionary, checking which synonym is actually appropriate, etc. Slow, painstaking work without good language-knowledge, but not impossible.
The problem is more, as mentioned, when people who think they speak a language quite well decide to do approximate translations without putting the work in.
Even professional translators, IME, spend a lot of time and effort making sure they have the right word for a given context.
Generally, people seem to confuse interpreters and translators. The former need to know both languages well, but aren't expected to translate every nuance. The latter need to get it right.