Just a quick comment here.
Perhaps you should not answer on behalf of that photographer for rejecting you as an assistant. There are many signs of miscommunication in the scenario that you just described. Talk to him and tell him your emotional discomfort for being rejected w/o looking at your works. If you don't, you are simply assuming that he is discriminating you based on your personal interpretation of his behaviour (rejection).
I happen to be reading a psychology book right now. This is a good example of fundamental attribution error - the tendency to overestimate the influence of internal factors in determining behaviour while overestimating situational factors.
It's 5am. I'm sleepy but i'll cite one example. If a man rushes to a hospitial to see her dying mother. Along the way he knocked into you without apologizing and left. Are you going to say that he is discriminating you without you knowing the fact that he has his personal reasons for behaving that way? So knowing that he is rushing to see his mother one last time, are you still going to think that he is discriminating you?
All i want to say is, go talk to that photographer again and thrash things out.
Last thing i, and many others, want is to see discrimination being associated with photography.
As for obstacles in advancing your career due to language barriers, i do think the best thing to do is pick up the language if your mind is set on doing it.