Though it does make me wonder when the correct spelling is out, why the translators don't automatically shift to the correct spelling there… Even now we have "Thriller Bark" as the confirmed correct spelling I'm still seeing incorrect name usage.
Mind you, this also goes for Logue Town... Which is spelt "Rogue Town" the 4Kids dub way. When we've all seen the sign saying "Logue".
Well… while I prefer "Thriller Barque" myself, as it just makes more sense, Oda's English isn't perfect, and apparently neither is that of his editors. Unless he really meant to name the island after the side of a tree, or a noisy dog... that cerberus isn't that important, is it?
And I guess some translators just decide to keep the names spelled the way they want it... in the end, it's really a matter of personal taste... though keeping true to the manga is probably the 'right' thing to do.
And in the case of "Rogue Town", you're taking an example from the 4KIDS DUB. They like to edit names of everything to their heart's content, see "Zolo", "Navy", and "Portgaz D. Trace", for starters. "Logue Town" was obviously intentional; it being the place where Gold Roger was born and died, Logue Town is the town of 'beginnings and ends', 'epi_logues_ and pro_logues_'.
But yes, Oda does make mistakes here and there, he doesn't speak English! So obviously that makes things a little more confusing for translators…