I hope I didn´t confuse you too much. :) What I wanted to explain with my examples is, that in different languages you may say a word the same way, but you spell it in completely different way.
And vice versa if you would write it down in the same way, you would pronounce it completely different by saying. Hope that´s a tad more clear. Sorry for my confusive speech. :(
I´ll try to explain my whole point with this scenario:
Oda wants the islands name to have an english name "Rough Tale". But then when it comes to writing down the name, he has to do it in a language specifi way, so that when japanese people read it, they say it Raftel. So in the end it is intended as Rough Tale, but for native english speakers it clearly isn´t Rough Tale when they here the anime.
BUT when you watch the anime you´ll notice that the japanese voice actors pronounce english terms completely different then a natice english speaker would do it. Unfortunally I can´t think of any term right now. But I hope you get the idea.
In plain words, if an english person and a japanese person would say Rough Tale it wouldn´t sound the same. Even if it is the same word. And when you write it down in the two languages the difference´s are even bigger with Rough Tale in latin and Raftel in Katakana. Now could that be the case?
Hope that was less confusing. :)