The keystones being automatically transfered to the personal inventory stumped me on my first tomb at Shang Simla. Good luck! When you enter the Temple of Heaven, there are two keystone panels. The other one belongs to another adventure with the notice "In Aid of Monks".
And, I agree with Samdiatmh, that tomb is tough. It took my Sim nearly 2 days to find the axe and the tomb symbol and get out again using another route. I used escape dust twice because my Sim got too tires and potion of courage three times because my Sim was too frightened by bugs and steam traps to explore further and then I used escape dust again because I just couldn't figure out how to get out of the chamber with the tomb symbol and my Sim was too tired to Zeneport.
I realise that I'm probably off topic, but Forum, if there is another way out, please feel free to enlighten this newbie.