Importieren:
$fc = import-csv Input.txt -delimiter ";" -header "Knr","Anrede","Vorname","Nachname","Straße","PLZ","Stadt","Land"
Konvertieren und schreiben:
$fc | foreach {$_.Anrede+";"+$_.Nachname+";"+$_.Vorname+";"+$_.Straße+";"+$_.Land+
";"+$_.PLZ+";"+$_.Stadt} > Output.txt