There is a problem with how we handle the 3" floppy interface, I see problems accessing B: for the PCW driver, don't know if it is related but I plan to iron it out some rainy day with a logic analyzer and compare with how MAME handles it. It is related to disk select and the ready signals I suspect
Most of the settings aren't that obvious, because the NCR5380's simplicity means that the adapter has to work the poor host CPU a good bit harder. Some of the settings registers have only one or two functional bits; others are expected to contain one of several seemingly arbitrarily chosen values. There's one which gets individually read out from EEPROM into RAM but is completely ignored by the BIOS after that.
The ASC-88 User's Manual would probably give a meaningful overview of the card's capabilities, but that hasn't been found either.
I think the best thing might be a conventional bezel. Something custom so that it can't look wrong. Same with the tabletop games. But for the panoramic ones, a logo and buttons should suffice. Nothing too fancy.