Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Size
PRIM_FRACTAL_LENParameter: Width Segments
PRIM_FRACTAL_SUBWParameter: Depth Segments
PRIM_FRACTAL_SUBHParameter: Rough Furrows
PRIM_FRACTAL_ROUGHParameter: Fine Furrows
PRIM_FRACTAL_FINEParameter: Scale
PRIM_FRACTAL_SCALEParameter: Sea Level
PRIM_FRACTAL_BLEVELParameter: Plateau Level
PRIM_FRACTAL_TLEVELParameter: Multifractal
PRIM_FRACTAL_MULTIFRACTALParameter: Seed
PRIM_FRACTAL_SEEDParameter: Borders At Sea Level
PRIM_FRACTAL_BORDERSParameter: Spherical
PRIM_FRACTAL_SPHERICALParameter: Switch to Updated Landscape
PRIM_FRACTAL_SWITCH_TO_UPDATED