My highly esteemed fellow Pathfinders, I must point out that The Professor gets his findings regarding the reading of ancient osirani from the GCS on pg 220.
It states:: Modern Osiriani readers can, with some effort, decipher writings made in Ancient Osiriani. ::
Now PFS uses different rules sometimes and what not, and Josh has final say of course, but the esteemed Professor Forthlake of the Almas University was indeed correct in his synopsis. However, Linguistics has had other changes in PFS that differ from the normal 3.5 pathfinder setting, such as humans no longer getting their home language for free. This was first seen in the amazing genesis of the awesome pathfinder time period known as the "Rise of the Runelords era". It was a wonderful masterpiece full of Thassilonian lore and history. We have preserved some of it here in the Magnimar Lodge, however most of it is gone. It is mostly now only available from unscrupulous Aspis Consortium agents, who hawk it for lots of coin on the mysterious and dark markets of ebay.
Regardless, may the open road always find you with adventure and the sultry kiss of Calistria's warm attention bless your path with luck.
Summarraniivayla, Pathfinder and Servant of Calistria