It is not necessary to import aircraft.
This is only necessary if you want to create a flight plan and then import it back into FS. e.g. for Airbus / PMDG. You can also set the fuel and load via FSrealWX.
In the Aircraft Editor you will find the menu "Load Data from FS" -> "Load from File".
Import aircraft or enter data and then save.
Then open the "Aircraft Assign" window and load the config. Then assign the current aircraft.
So you only need one config for different liverys of the same aircraft.
I will continue to expand the manual.
If you find an error, then please give me exactly about your system. Which sim (FSX / P3D / Xplane). Which connection (FSUIPC / SimConnect / FSrealWX-Bridge). Which OS.