War doch schon ein sehr guter Ansatz ;).
Spoiler anzeigen
[autoit]
Global $Nations_Array[4] = ["", "Schweiz", "Frankreich", "Deutschland"]
$var = IniReadSection("C:\Documents and Settings\User\Desktop\Test.ini", "Nationen")
For $i = 1 To $var[0][0]
For $j = 1 To UBound($Nations_Array) - 1
If $Nations_Array[$j] = $var[$i][1] Then IniWrite("C:\Documents and Settings\User\Desktop\temp.ini", "Nationen", $var[$i][0], $var[$i][1])
Next
Next