Hi…,
Welcome.
As per FAQ - Missing Airports,
We derive our FMS Data and Charts from Jeppesen - a professional navdata provider for major airlines worldwide. The airports included depend on which airports are required by their real world customers.
With the exception of the old Kai Tak airport at HK, we do not manually add airports to these databases.
So it is a significant undertaking to add all the navigation data and charts for an airport, hence we rely on the data and charts provided by our supplier.
Cheers
Ian