Place an on change microflow on your City selector.
In this microflow check if Data_OriginCity != empty, then if not empty retrieve the Origin_City associated.
Then retrieve from database Origin_Country based on OriginCity.ID
Then set Data.Data_OriginCountry with the retrieved Origin_Country, be sure to select refresh in client.
Edit:
If you do have the OriginCity_OriginCountry association, just retrieve Country over assocation.