There are plenty of factors of why we don't have any revelations in most languages. First of all we should understand that we believe in the Prophet Mohammed to be the last Prophet. This gives us:
- Many of the languages that exists today, didn't exist for more than 1400 years ago. They have developed into the current language. For instance, Latin has developed into several languages.
- The languages might have gone extinct without our knowledge.
- The people might gone extinct.
- The message/revelation might after time been altered and by time and alteration become something that we today never would know that it really at the beginning once upon the time was revelation. This could happened by many factors:
- By time, the people's understanding of their own old language changed and made them interpret. After more time have passed and their language has been changed completely, so have their interpretations been changed to fit their understanding of their language. Then interpretations on the interpretations make it become something very different
- Somebody alter/change the religion, and the people do the same. By time the old religion is forgotten and no trails of the old one are left.
- Nowhere to store the revelation. (for instance, no books). Many Prophets came with the message without a book. Also our definition of books might not have been existing that long.
- As the "new" religion come, or the "new revelation", the people embraces it, and by time (lets say 100 years) remove all connection to their old religion. And that time they might not been storing things like we do today.
There are so many things we don't know, which makes it impossible to really say what happened.
Why religions change and disappears has many factors too. As Muslims we have always been memorizing the Quran in the original source. This forces us to to not forget about the language. We are very strict when it comes to alterations and innovations. A proof of this is just to look at the Arabic, how many still understands it, and how little it has been changed in comparison to other languages that once was the fundamental source of a religion. If a Moroccan and Iraki speak, they will understand each other. If a Swedish and German speak, they won't understand a word.
It's an interesting subject. I would argue that the Quran is the reason, and the way we as Muslims store the Quran (its language and message)
If we look at other religions that exist today, according to our belief, they have been altered and changed. And a big reason why they've might have done so is because of the language and because of the languages development, and also their way of storing it has not been as effectual as our way. Many of these use translations of translations of translations.
For instance, the word Father, that Christians use, could have in their time been a word that meant something like the Arabic word Razzaq, or Rabb, which all Christians might have understood in that time. (note the word Ab (father) and Rabb are really alike in many ways). Is God a father, or is it a metaphor to describe God as being the one that takes care of his "children", i.e his creation or slaves? We call God for Rabb many times. There are instances in the Arabic language when it's possible to call your father for Rabb or the one in care of you or your master (see surat Yousuf:23). You also call the person that has raised you for Rabb. A person that is uncouth (not raised well), is called not "morabbi".
These points are valid before and after the Quran.
Due to the nature of language and its way of developing, the revelations might be lost as the language changes. Altering the revelation (intentionally or unintentionally) several times without storing the original message. Destruction (extinction) of a people (and their message).
An example of this in language is that there are words that we are using that we know holds some metaphorical meanings, but where, when, how and why these meanings developed is too old for of our historical record (see here about left and right).
These are all possible reasons to why we don't have the "revelation" we consider to be revelation in most languages on earth.
Why I said that we should understand that we believe in the Prophet Mohammed to be the last prophet is that since 1400 years there hasn't - in our beliefs - been any more revelations since then (not to question your beliefs). Under those 1400 years (even more), languages and other belief system that existed in that time might/have changed extremely, to a degree that if you would compare the original belief system (which is unknown) to the one today - that you wouldn't be able to identify them as alike. This is might be why we don't have revelations (as we define it) in most languages on earth.
At the moment we cannot compare language X and it's belief system without it's origin language and belief system when it's missing.
For instance, X + y. We cannot do anything with this equation, even though we know that X = 10. We still need y to be able to draw real conclusions.