Hidden trackable information in games sucks!
I play games for fun and pursuing the goal to win the game is fun! :)
This is explicitly stated on p. 2 of the rules of Wonder Pack:
P. 2 of the rules of Wonder Pack wrote:
If multiple players take cards from the discard pile during a given turn, the resolution order is the following: Halikarnassós, The Great Wall, Manneken Pis, Salomon and finally, the Courtesan’s Guild.
There is a more recent rule since the publication of 7 Wonders: Cities Anniversary Pack, adding Counterfeiter's Office to the list:
P. 4 of the rules of Cities Anniversary Pack wrote:
If multiple players take cards from the discard pile during a single turn, the resolution order is as follows: Halicarnassus, The Great Wall, Manneken Pis, Solomon, the Counterfeiter's Office, and finally, the Courtesans Guild.