I happened to catch a TV documentary the other week about Koxinga, a celebrated Chinese pirate/warlord of the mid-17th century who is most notable for initiating the Chinese 'ownership' of Taiwan by wresting it from the control of a small Dutch colony in 1661.
It's one of those names that I've never heard spoken before, but I'd always assumed that its spelling was derived via pinyin or some similar modern Romanization system. But I really have no idea. It could be a much older spelling. I wouldn't even know what variety of Chinese it is supposed to be (his paternal family were supposedly from the southern coastal province of Fujian; but he himself was born on the island of Kyushu at the southern end of Japan, and had a Japanese mother). And after all, the chap was born nearly 400 years ago; it's impossible to know exactly how various versions of the Chinese languages of the time were pronounced.
Even so, I would have thought that the favoured pronunciation today would follow the pinyin rules, under which x is a sort of sy- sound (not as in psychology, but as in this year), and the o would be a long -or: Korsyinga.
This TV programme's favoured pronunciation, Cock-Singer, just didn't sound right, somehow; it lacked a certain gravitas or dignitas.
[I learn that the name is an honorific title, signifying something like 'Father of the Nation'. In modern Mandarin Chinese, it's 國姓爺, guo xing ye, where the xing part is most definitely a sying, NOT a -ksing! Whether Fujianese or Cantonese (as spoken 400 years ago) would support the more unfortunate innuendo-laden pronunciation, I cannot say.]