First of all, I wouldn't rely on automatic translations for the translation of a questionnaire. It is one thing to use some of those tools to understand a text, it is another thing to use it as the actual translation for a questionnaire.
I use Google Translator quite a bit during my daily work. It pretty good - most of the times. But it also can go terribly wrong. I would use Google Translator only to help me with translations from and to languages that I know pretty well.
I have seen that you are from an Australian University. I am pretty sure, that you will find a German, Austrian or Swiss exchange student somewhere there. And I am pretty sure that if you invite them for a drink or a lunch they might be willing to help you out with checking the questionnaire for you.
Because the way it is, you could also invent the results and you wouldn't loose much in reliability.
I would even say that the data would be more reliable if you would sent the questionnaire to German speakers in English. If they don't know English, they just won't answer (i guess).
But with the current translation and the mix of languages, it is very difficult to understand what you are talking about and I doubt that results will be any helpful at all. I personally wouldn't want to base analysis on this.
Just to give you an example, how little things can impact a survey:
We were running a survey in several countries, over several years in different waves and for several brands at the same time. My Italian intern decided that a little fill word in one of the questions was not necessary in Italian and deleted it.
When I received the tables we suddenly had an increase of 10 percentage points to the previous wave of the survey and to the other countries (on average over all brands in this country - around 15 if I recall right).
I was a little surprised about the increase and couldn't really explain it, so we went back to the data and the questionnaire and finally found out what was the case: deleting that little fill word caused an increase of 10 percentage points. Not nice to explain your Italian clients what happened and why we deleted this word, which was in this questionnaire for about 4 years. Well, I actually had no good reason. I couldn't really blame the intern for it (even if it was her fault, but wouldn't look good). So I had to take it.
Just a little story from the research world and why details are important.