@Crossword:
Ah, didn't notice that. It only came to my attention since spellcheck was flagging ''Rumbar'' but not rumba. So I guess this is probably a case of a pun being obscured by Engrish. Carry on then.
What the heck…? Where'd you go?
Oh man, I deleted my post after I found a post where someone claimed Oda had spelled it Rumba (don't ask me in what language)several times before realized it's a manga spoiler. For some reason looking over the thread that discusses this very matter (About Brook's crew…) I don't see if they came to any conclusion even though Ivotas claimed this was already cleared up earlier in the chapter threads. Interestingly I didn't find any posts addressing that in the spoiler- and chapter threads of ch489 o_O
It should be mentioned though that Stephen also decided to go with Rumbar. But you can't really expect us to do this kind of research. Quality groups on the other hand better know exactly why they went with the spelling they choose :p
Also here the pic I deleted earlier (totally because of spoilers :D )
!