Preface: I'm still a rather inexperienced junior software developer working at a German start-up company for about 2 months gathering my first experiences of "the real world".
I am currently dealing with a foreign contact about implementing an API of theirs. Only problem is that unlike the last time I had to do something like this, it now is all in a language foreign to me. I have to implement an API where everything is in Italian: the data being sent from the API as well as the documentation of said API. I got a 3 page "description" on how to get certain data but this description document explains Italian variable names and values with yet more Italian words, which makes it almost impossible for me to work on implementing it into our own systems (more specifically mapping the values correctly so we get usable data into our databases and the correct places).
I went back and forth with this guy and today I asked him to translate a few things of the original Italian documentation that are relevant to me and my work (not the entire 28 page thing) and he's either unresponsive or sends me back the full 3 page description I already had when I was assigned to the job. It seems like there is either a language barrier or he just doesn't care and will keep copy-pasting the same 3 page document into every inquiry I ask for help.
My superior expects me to implement the API on the basis of "Well, we have to make do with what we have" (he's the senior developer and IT lead) yet I'm having serious second thoughts if this is even going to turn out at all. Although there is a colleague who speaks fluent Italian she's caught up in her own work and can't be spared at the moment which she made perfectly clear to me the first time I asked for her help in translation. However, she has said that she cannot make sense of it. I also don't fault her for being unavailable.
Trying to translate the documentation via a translation service like Google Translate or the integrated MS Word translator (probably Bing) turned out to yield unusable or incomprehensible results. So that is not an option.
So the main question for me at this point is: How am I supposed to respond in a professional manner to either the unhelpful responses from my contact person as well as the lax views of my superior towards me implementing an API I can't even begin to make sense of its data or usage?