Add your own keywords from your metadata to the gpt.properties file in the ISO category you want each layer to be shown.
In my metadata the layers used by the planners has the keyword 'planning'. So I added the word "planning" to the appropriate line for keyword search:
catalog.harvest.lookup.keywords.planningCadastre =planningCadastre: planning, parcel, parcels, ownership, public land ownership, PLS, public land survey, section;