The GBS-8200 actually only supports analog RGB, not digital as with CGA.
A resistor network to do the level shifting is possible.
And its whole named purpose is CGA/EGA/YUV to VGA.
The converter even has a special 5-pin CGA/EGA connector.
How this should be taken?
YUV is analog SoG.
YPbPr is the same with gamma correction.
So SW button is a sync mode selector.
But YUV is not RGB so it must be a color space selector too.
Back in the day VGA resolutions were available before 15-pin D-sub became standard.
Anyway, RGBI needs that intensity signal and is't not available anywhere.
I'd say that component video to VGA converter is much better name, even that it excludes higher frequencies.