Hi there,
The name of data source synced trait is exactly similar to data source name.In order to search for it,type in the data source name in search bar and the data source synced trait for that particular will appear.For e.g.

Data Source Synced Traits track all of the users associated with a data source. Data Source Synced Traits are useful for troubleshooting.If your selected trait returns data, that indicates the ID synchronization process is set up properly and pushing data to Audience Manager.
Also when we talk about offline data,we always talk in terms of CRM Id associated with a customer.Updating the profile merge rule to no authentication means authenticated profiles will not be considered during segmentation.
If your looking for steps to validate IDFA/GAID implementation,you can refer to below link:
Implementing AAM for Android
Regards,
Shweta