Hmm - then one wonders how the Grey Fox was able to change them if they were unreadable, then how could anyone write them?
Lol...good point.
Forgot about that! Well, perhaps Lady Nerevar is correct; "anyone can read them, but with mixed success."
One another thing the OP made me think of is something that is almost certainly not answerable from lore (though perhaps it is?), and is most likely just my own speculation, but still: the Elder Scrolls, while certainly containing things like muddled fates and destinies, swirls of possibilities, and accounts of history, perhaps part of their power is not simply in the "absolute truths" regarding the past and future in the scroll, but rather in the interpretation of what is on the scroll? In other words, instead of just prophecies that must be deciphered, maybe they are much more flexible and open to many interpretations, and it is the interpretation itself that creates a fate?
I'm not sure if this makes sense, so here's an example of the two types of scrolls I'm talking about. Scroll A: A mystical, muddled message that warns that the Emperor will be assassinated; once the message is deciphered, something can be done. Scroll B: A mystical, muddled message that could have any number of possible meanings, and the reader interprets the scroll and in the process, unknowingly creates a fate from their interpretation. With Scroll A, it is a simple matter of: Figure out what it says, then act accordingly. With Scroll B, fates are tied to the interpretations of the scrolls, and the scrolls meaning/content is not fixed; fates are created by mortals, rather than by the Scrolls.
Again, this is purely speculative-- just something that came to me.