This one is actually adapted from some code in Fall from Heaven 2, so credit should go to them. Basically, if you have the wonder and a unit is killed defending or attacking any one of your cities, that city gets a culture bonus equal to the killed unit's experience (plus a small base amount that scales depending on game speed).
All the python is labeled and searching for "Terracotta" should find the changes. I recommend using winmerge to help combine the files.
Python, XML: me (tsentom1)
original python: Fall from Heaven 2 Team
Model and Button: hrochland
Wonder Movie: Arian
Terracotta Army Wonder (XML+Python) 2016-10-05
Terracotta Army Wonder (XML+Python)