The PropertyTemplates.xml file contains all the property pane layouts for different object types. Note that the property pane layouts for different object types are treated separately. For example, Tekla Structures can read the property pane layout for steel beam from a different location than the property pane layout for steel column.
If different object types are defined in different folder locations, the definitions are combined. If the same object type is defined differently in different folder locations, the definition that is higher in the search order is used.
The property pane layout in the ..\Users\<user>\AppData\Local\Trimble\Tekla Structures\<version>\UI\PropertyTemplates\ folder has the highest priority, and after that Tekla Structures uses the default search order.