The calc_results functions for cross-border flow (ac_export_per_country, dc_export_per_country, ac_export, dc_export) do not return the absolute amount of electricity exported or imported over the entire period, but the difference between these two, ergo the balance of imports and exports. Therefore, using the function tells you whether Germany acts as an exporter or importer, but it does not tell you the total amount of electricity actually exported or imported, as the function names and descriptions suggest.