It looks like my OP was about as cryptic as usual, maybe more so? Whatever, lets try it with some more on point visual aids.
Here's why the SE Card is so important, the interface between VidCard and breakout panel board is a 16 pin IDC header cable. The DA-15 will hopefully have the bog stock Apple spec pinout. With a little continuity testing and a bit of luck, I'll have the mysterious DE-9 Video Interface from the stone age of Macintosh Display Technology figured out.
Since I haven't even got an SE for testing, the first card I snagged on a lark was intended to explore DE-9 VideoVoodoo with the IIcx. It turns out this NuBus card may very well be much handier than I'd hoped.for a second reason.
Note the unimplemented HD-15 thruholes next to the DE-9 Connector! VGA and its HD-15 connector were introduced by IBM in 1987, three years before this ©1990 NuBus Card. So I've got two chances at finding a conversion table from the ancient DE-9 video interface to a documented VidCard interface from a more recent era of Macintosh Graphics Cards.
The listing called this an Apple Card, we'll see when the results from DeclRom spelunking are in. I'm guessing it was made by a third party unconnected to either Apple or Radius. I didn't see any info on the development dates for SVGA or XGA in a quick search, but it stands to reason that a VidCard mfr. might have doubled down their bets by supporting both the then standard TPD interface and emerging Video Standard technologies
We shall see.I know olePigeon and a few other folks here that will be very interested in any results that might be forthcoming.