I believe habisain said in one of these threads somewhere that it's much more important to be 'good at' (paraphrasing here) English than to be good at Japanese, and I fully agree with them. Well, more specifically, much more important to know the language you're translation TO (target language) rather than FROM (source language).
No matter what the language, there are nuances and such that will never carry over into another language. But having an excellent understanding of your target language means having a good understanding of language in general and how to communicate various ideas and concepts. Even working with a language you don't know, using machine translation from multiple sources and being able to weed out the bad options, and then applying logic form looking at the structure and context of what's left, will give you a rather serviceable result. The general reader will be much more interested in whether or not the resulting text makes sense rather than how exact it is when compared to the source material. Clearly, direct instructions and such are very important (numbers and directions should carry through), but when it comes to things like the terminology used, it doesn't matter if the translator changes it as long as they are consistent with the change.
All that said, I thought you did a great job with D&P. If I encounter something in a translation that seems really off, sometimes I start wanting to dig into the original source to see what the changes were, but I never experienced that here.
Not to say that there's no value in someone who excels in both languages when doing a very accurate and true to source translation, but then, they'd probably make a job of it.