It seems the filter model parameter is not yet available via LUA. I did a search and couldn’t find it being reported.
5 parameters are available: type (1), cutoff (2), resonance (3), Q (4) and inertia (5).
Possible work-around is to set renoise.song().tracks[].devices[].active_preset_data
EDIT: Similar issue found in stereo expander, parameter “mono mix”