The HK subs are just spelling after how the names were pronounced in Chinese. You see, Chinese language is different from Japan/English, and they don't have every words that pronounce the same as Japan/English.
In Chinese, Luffy's name is pronounced (not spelled) 'Loo-Foo'. It may soundlame to you, but it's absolutey okay to Chinese people. There is no word in Chinese that pronounces Fi. Chopper in Chinese is pronounced 'Chow-Ba'. Once again, you think it's lame, but it's pefectly fine to me.
Finally, Usopp is pronounced 'Penrenboo' in Chinese. Don't say it sucks, it's perfectly fine to Chinese and Taiwanese people. 'Penren' means lie, and that's what Uso means. We Taiwanese just translated the word Uso into lie, which is pronounced Penren. The 'boo' part is to indicate to 'pp' part.
If you think names suck in Chinese, then you should learn Chinese. You'll surely understand what I'm saying if you're Chinese.
It's just like saying thank you. Why don't people in USA say 'arigado' instead of 'Thank you'?