ConstA knob is a plain display value in CustomGeoJSONModuleConfig, at the path its id names.
The module draws with your own MapLibre styling, so visible is the only knob. These aren't knobs:
layers, raw MapLibre layer specs passed through untouched.cluster, MapLibre source options forwarded verbatim and fixed at creation, and
its sourceID, a name.images, image payloads, beforeLayerConfig, a layer placement, and events.
Every custom GeoJSON knob with its kind, description and default, as static data readable with no map loaded.