I just happened to stumble across my old Land 2 manual while cleaning my room and had an urge to read a little bit of it out of nostalgia and well:
The Syrup part can be basicly translated as "that rotten Captain Syrup and his Black Sugar Pirate Gang", with the manual using the maskulin "der" and "seine", instead of the feminin "die" and "ihre".
The English version on the other hand is completely gender neutral:
Just figured I'd share this little faux pass here, because I find it mildly amusing.
Except that Land 1 and it's manual already did that, so it's not new or a suprise anymore, not to mention that the Land manuals are written as if Wario was narrating them, which would mean that Wario suddenly forgot that Syrup is a woman.
I highly doubt that it's anything more then a translation error.
They probably just didn't know since the english version doesn't mention the gender either. In german there's no genderneutral version of "that". At least not one that you'd use to describe a person.
I have the Wario Land II manual and it comes with several languages. It appears there's a Spanish "el" too. However for us, the Portuguese translation isn't included in the fancy manual, and instead, it's printed on a separate very cheap sheet of paper (and which I strangely didn't preserve so well). It clearly refers to Sypup as male ("Capitão Melaço"). I would take pictures but I only have a potato here right now so I'll just scan this part instead... By the way, it refers to Hen as "she." "Syrup" is mistakenly spelled "Cyrup" and the word for Sugar also has a spelling mistake.