MapleStory 2, welcome.

now why is the empress called Ereb.

You may be familiar with how Japanese speakers frequently reverse their R and L sounds (Engrish). Korean-English (aka Konglish) speakers have two common letter substitutions:
English V is typically transliterated/pronounced as B. (Ereve in English is thus Ereb)
English F is typically transliterated/pronounced as P.

Two others that typically show up in more poor translations:
English L replaced by R. (Not nearly as frequently as other Asian languages, but can happen.)
English TH replaced by S. (My favorite example of this in GMS is Risell Squid. It is a bad transliteration of Lethal Squid.)

So, if you are having trouble figuring out why things are different between KMS and GMS, check the above things and see if you can figure out how they got be different.

EDIT: If you are unfamiliar by what I mean by Transliteration, it's not the same as Translation. Transliteration is going from one type of writing to another type of writing. For example: Hannukah/Channuka or Osama BinLaden/Usama Bin Laden. The differences in spellings are because the sounds of the language are different and are not meant for the Roman alphabet and the letters are an approximation.