Spectral Osc FilterData

Dear all,
I created a Halion instrument (Spectral Karma) which uses two synchronized Spectral Osc. There I would like to use the existing spectral filter as an additional powerful configuration component. For the time being, I am not able to set the SpectralOsc.FilterData attribute “manually” from a macro script. It seems that the existing userdata information there is somehow different from the standard envelope points structure. The access of the preconfigured sub presets (in Folder Spectral/Filter) is also not possible. They can be accessed but they are not applied to the spectral osc.
Has anyone an idea or solution for this problem. I analyzed the existing FilterData presets and it seems that every point in the filter description uses 8 bytes. Maybe an analog structure could be build in Lua? As the existing curve editor UI component does not show the values of the x and y components (a know bug?) I can only presume how the values are used.
The only thing that work is a direct connection between the FilterData attribute and a scaled curve editor component, but this is insufficient for my purposes.
Any help will be appreciated…