Where is this mysterious FrameMaker "SVG export" filter?

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This is a follow-up post to my previous thread titled "How can I save anchored frames as SVG during XML export?".

I've been mostly successful with using Inkscape for EPS-to-SVG conversion of FrameMaker anchored frames during XML export. However, FrameMaker's EPS export filter has a bug where it omits line properties (dashed, solid, etc.), which renders thousands of figures in one of our books incorrect (they use solid and dashed lines to indicate the result of geometric operations).

The venerable MIF2Go utility internally uses a FrameMaker-supplied SVG export filter, described in this post from 2010:

That's correct; in mif2htm.ini, you set:

[FDK]
GraphicExportFormat=SVG

Then Mif2Go tells Frame to use its native SVG export
filter. Note that we did *not* write that filter; it
is Adobe's. So if it does not match your needs, we
can do nothing about it.

So apparently FrameMaker *does* have a FrameMaker SVG export filter provided with it, somewhere. MIF2Go uses internal FrameMaker calls for its work, so apparently this SVG export filter is available internally but not externally via user-defined write rules.

Possibly related, there is this conspicuously named file in the FrameMaker installation root directory:

C:\Program Files\Adobe\Adobe FrameMaker 2020\SVGExport.dll

So I took a look at the maker.ini file in the FrameMaker installation directory. Interestingly, there is not an SVG export filter defined in the [Filters] list of export filters. Maybe I could add one and get it to work? So blindly I tried lots of variants (guesses because I don't know what I'm doing):

115="SVG " FRAM FrameVector SVG GFXExport "SVG" frame.exe ^.svg
115="SVG " IMAG FrameVector SVG GFXExport "SVG" fmexport.dll ^.svg
115="SVG " FRAM FrameVector SVG GFXExport "SVG" SVGExport.dll ^.svg
115="SVG " IMAG FrameVector SVG GFXExport "SVG" SVGExport.dll ^.svg

and none of them worked.

What is this mysterious SVG export filter that MIF2Go is using? How do I call it? Can it be made to work via simple write rules? Is it callable from ExtendScript?

Thanks in advance!