Viviane’s decipher isn’t just about the runes but also about a prophecy she read from the old book. My guess is that there were runes written in the old book as well and the stone helped her to make sense what that old book talked about.
Mission item screen too (easier to look it from here than looking it from another topic).
Is it possible that the’s error in the “asmaa” as well and it’s not “asmaa” but instead “asdaa” or “asdar”? E.g:
Den dag skall komma da sem asdar smedens ilska ger liv at metallen.
I don’t speak Swedish and got no clue if “asdaa” or “asdar” are real Swedish words. Though, when entering both words in the sentence, Google Translate gives the same result:
The day will come when the wrath of the blacksmith gives life to the metal.