I am not sure how that works?
It seems to be for airports with runways that have the wrong designation, which I don't think is the case here as the runways are simply not there, and for such a case it is stated in the runways.txt file that:
// C) if a runway in reality (and in Navdata) is existing, but is not available in FSX
// *** this case is not possible to assign ***
I don't get the errors anymore, however the runways are still not visible.
Perhaps you could give me an example of what I should put in the runways.txt file?
Simply putting in "EHAM 18R" and so on did not fix the issue.