Only thing brits get pissed off about is calling the UK England, because all the countries hate England including probably the English.
I don't see how it's nonsensical. Makes perfect sense to me. Call the country what people know the country as. You want to call the United Kingdom, Kingdom United do it. You will obviously get raised eyebrows because you will only be the one calling it that.
You still haven't answered the original question why westerners insist on calling CPC differently from what it officially calls itself or what the rationale for that is.
It means that you think you've answered the question when you very clearly haven't. Again, the reason people in the west would choose to intentionally keep misspelling the name of the party is very clear, but if you feel the need to keep doing mental gymnastics you do you.