I think that cultural appropriation can get extremely confusing, since basically every individual in any given culture is apt and entitled to have a different opinion of it; what bothers one person might not bother another. And then on top of that, the intention of the "outsider" in playing with that culture can always be different than the next person's. So there's no one-size-fits-all "right" or "wrong" there, in most cases. On top of that, there are additional layers of nuance to the question, such as: "How many generations removed can you be from the country before it's not appropriate to use/wear/practice the cultural item anymore?", "What percentage of one's ancestry should hail from that culture before it's not okay anymore?", "If you can 'pass' as a member of the dominant social group (e.g., say you're 1/4 Japanese but look like your 3/4 Irish roots), is it not okay for you to flaunt that part of your ancestral culture, given the appearance-based privilege you'd be presumed to hold?" And so on. I think these questions and the various permutations of answers can go on endlessly, and as a social sciences nerd, I'm really fascinated by that.

That said, I do feel sympathy for people whose cultures were so denigrated, for so long, and whose roots were "lost" via forcible relocation, slavery, etc., and I think I can understand on some level where a lot of the anger comes from. It's a delicate, tricky topic.

It's cool that you had such a diverse upbringing. I come from a similarly diverse place, where, interestingly, "What's your ethnic background?" was a very common, friendly question and not at all a taboo. It's interesting how much things change, and how even the same thing (e.g., that very question) can mean such different things to different people. That said, I try to do my best to adapt to the times and be respectful because, well, when did trying to be respectful ever hurt anybody? ;)