I have been on the hunt for over a week now with over 70hrs of looking into the game and possible clue. I am unable to find the "context" of the clue to be able to decipher anything from them. I thought I would list some of my findings to help future people maybe figure out something I am unable to do.
There are 6 different pictographs that make up the writing on the monolith. I am unsure exactly what they are supposed to be but seem snake like in their imagery. All 6 different images can be found on the temple floor along with other characters.
The other characters I have found throughout the game in different images and levels. There appear to be a total of 13 different ones. When looking at them my mind wants to convert then into letters or words but there is a problem with this thinking. Stated in a previous comment is that ones language should not hinder anyone therefore the images are likely to be ideas or numbers. If language doesnt make a difference the key would likely be number or a proper name where spelling is the same regardless of language. I have tried binary, translations from and to Galician, and number sequences to no avail.
After reading though interviews and the history of the making of this game I do believe my issue is "context". I understand we are looking for a password but what is the password based off of. Is it this:
"Who is behind this prison-fortress and its intricate secrets? Explore all rooms and find the key to solve the mystery that will lead you to an incredible and elusive treasure!"
With many other treasure hunts you are given the first clue or the idea of what you are trying to put together. Examples of this are Merlin's Mystery where we knew that we were looking for the ingredients and words to cast a spell long forgotten or Fenn's treasure where a cryptic poem started us off into the Rocky Mountains.
Then there is also the issue of are the clues exclusive to in-game or is outside research needed to understand the scope of the clues such as French Sociology.
I will continue to look but wont have the amount of dedicated time as I was able to have this past week. Good luck to you all and hopefully I was able to help someone if I am unable to find the treasure myself.