That's just it though, they
aren't well-emulated, at least not in MAME. The black-boxing in MAME has multiple notable issues, from Zelda's Adventure hanging when you try to walk to another screen, to certain games lacking sound effects and/or music. It's probably down to me not understanding the code you sent me at the time, but unfortunately I've long since lost access to the e-mail address which you sent the code to, so I can't even check anymore.
As I see it, since we have dumps of SLAVE and SERVO, it's preferable that MAME emulate them rather than going the black-box route. MAME is ostensibly meant to be a documentation project first, with playability being second. With that in mind, I'm perfectly fine taking my time with the CD-i driver in MAME (which I'm currently taking a break from to work on some discrete games) and directing people to use CD-i Emulator in the meantime. Though, admittedly, it's a tough sell since a lot of games on the CD-i were absolute shovelware, and I would wager most people just want to fire up the games long enough to do a playthrough for YouTube, and don't necessarily want to buy a commercial emulator. Still, CD-i Emulator is cheaper than buying a real CD-i console, and it has rather solid compatibility, and quality comes at a cost.
