The support for importing GML application schemas is covered by the XML Schema Import. Below is an excerpt of an imported Inspire CadastralParcels schema:
HALE offers the possibility to load a schema based on a WFS DescribeFeatureType KVP request. You can specify the request URL manually or use the ... button to launch a wizard assisting you in building the URL based on the service capabilities.
When determining the URL based on the service capabilities, you can specify the feature types to select from the server. If you don't select any types, all feature types will be requested.