I am a native Czech copywriter and translator from English to Czech. Sometimes also translating to English or creating texts in English (cooperating with a native speaker for the final proofreading). I believe that a really good translation requires more than just understanding. You need to REALLY get the meaning and you need to be able to recreate it in the target language. With the utmost respect for the original text and its meaning, but not mechanically. If one easily recognizes the source language in your translation, then it is not a good one.