I know this was asked a long time ago but for anyone else who has managed to find a link and download this brillient mod but has this parking issue I think i've found a solution. This seems to work for me:
Go to SteamLibrary\steamapps\common\EMERGENCY 4 Deluxe\Mods\Kent Mod v1.2\Scripts\Game\Command
Rename ParkVehicle.script something else like ParkVehicleOld.script
Rename "Ausrichtung.script" to "ParkVehicle.script" and run the game.
There is some kind of problem with the custom script causing the error:
?Tried to assign unknown command 'Bereitstellung_drehen' to object U
!WARNING: global listener object is still registered! Unregister listener before destroying object!
If anyone can help identifty what that might be I'd like to help fix the modified parking script.