As I said when I mentioned it in my earlier post, I do not think it's "decisive" at all. If you read the statement you quote within context it does not really say what you imply. It says that you can't have fully automated translation (i.e. change a text from one language to another, rather than understand the meaning of an object used as a symbol).
On the other hand, the guideline from the corebook is extremely clear: learn one visible property of an object (a property that someone with appropriate skills could determine just by looking)". So if you see a stone with a glyph inscribed, you can learn the meaning of what's inscribed on the stone, since someone with the appropriate skills could do it just by looking. You are not dealing with thoughts, you are dealing with a warning-stone.