Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Cameras
GLTFIMPORTER_CAMERAS
Parameter: Geometry
GLTFIMPORTER_GEOMETRY
Parameter: Materials
GLTFIMPORTER_MATERIALS
Parameter: Normals
GLTFIMPORTER_NORMALS
Parameter: Phong Angle
GLTFIMPORTER_PHONGANGLE
Parameter: Vertex Colors
GLTFIMPORTER_VERTEXCOLORS
Parameter: UVs
GLTFIMPORTER_UVS
Parameter: Flip Z
GLTFIMPORTER_FLIPZ
Parameter: Split Meshes
GLTFIMPORTER_GEOMETRY_SPLIT_MESHPRIMS
Parameter: Transform
GLTFIMPORTER_ANIMATION_TRS
Parameter: Pose Morphs
GLTFIMPORTER_ANIMATION_POSEMORPHS
Parameter: Pose Target Layer
GLTFIMPORTER_ANIMATION_POSEMORPHS_TARGETSLAYER
Parameter: Clean Tracks
GLTFIMPORTER_ANIMATION_CLEANTRACKS