I am experieneced as a coder and I could feel your frastration without or with little documents when strarting a new project or assignment because I had the similar feelings many years ago. However, I really feel the documetation is not so critical now, most of time, I don't care because the code itself can tell you a lot, especially, if the code is well structured.
In my opinon, a developer should focus on business knowladge , operation process and change requirements. When you got the points what to change, you could find a lot of clues how to get the points in the code.
You need work on your own to solve the problem, not expecting others to lead you step by step. I don't mind helping my teammates, no matter what natinality is, but I would not be willing to say too much if my opinion was not taken serious. On the other hand, what could I say if I were facing a stupid questions.
For your situation, I recommand you send a question and requirement list to your peer, PI, and Manager when you starting a new assigment after your analysis. No one could ignore decent questions, and you have the records to document what thappened.
It is not fair to expect special support from your chinese fellow
My two cents
