It is alphabet based and I am 95% sure that the initial phrases were in french. That language I do not know alas. The kami writing could be deciphered if the researcher in charge would be a french-speaking one. And I also posted instructions for deciphering alphabet-based ciphers:
A short master-class in deciphering alphabet based-ciphers
Deciphering alphabetic scripts is not that tricky really. First you look at those letters that are repeating more often than others - usually it means they are vowels. Then when you have a set of possible variants for each you go for 2-3 letter words (better yet same words that repeat themselves throughout the text) these are either prepositions or things like "the" "a" (forgot the term. It's called artickel in russian After that you start browsing through the text putting in various "kinda deciphered" vowels and the like. It helps a lot when there are things like names of people or places that you already know. It would be Ma-duk in the kami writing for example. So going on like this you get as many letters as possible and then start deciphering the sentences checking for errors in collected letter info and filling (guessing) gaps. Do that until you have ALL letters and voila.
Hope this explains it
As for the symbols on the roads, I am 100% sure they are pure ornamentation...
At least now we know where the renegade devs have been exiled to 
