Why, Curse of Monkey Island, is only in English Language?
Originally it was translated and dubbed in many languages, why now is only in English?

The german version of it, is absolutely wonderful! I'll buy this when we have multiple languages to pick from.

I think this is one of the best translated games I've ever seen. The Spanish version is wonderful.

the french translation is very nice too, i hope the game will be updated with new language (i already bought because i have no will xD and lot of hope xD)

+ Multilanguage Version

The italian dubbing is good too!

Yeah, I remember the Spanish dub being really good.

Yeah, I'd like to see the other languages as well. The German version is absolutely fantastic, I actually prefer it over the English one.

I hope this comes in german like the original game i own

If you want to get in contact with the people who translated them to negotiate the rights, I'd suggest you get started.

Are we talking about fan dubs or something? Lucasarts wouldn't not own the rights if they were recorded for an official release.

It's surprisingly common for localizations to have a different rights holder than the original version of the game. The translation/recording in these cases were done by a third party. This is why sometimes a game on GOG lacks some languages that were released back in the day.

I don't know if that's the case for Curse.

You'd be surprised what can get blendered during a buyout, in addition to what Cæsar said.

Edit: Additionally, certain voice actors might have a royalty clause or other complicated clauses.

Look at the game folder, there's "Language_setup.exe" inside. English, French, Italian, German and Spanish subtitles are available. ;-)

SUBTITLES.. not voiceover.

The german dub is better than the original in my opinion:
https://www.youtube.com/watch?v=MUc4OTvAxgY#t=1m30s