MAME has a driver for the CD-i but support is incomplete, as it still doesn't emulate the Digital Video Cartridge (DVC) as of May 2019. That means games that require it like 7th Guest, Atlantis - The Last Resort, Creature Shock, Dragon's Lair and Lost Eden are unsupported. However, MAME is much easier to control, and its audio emulation is actually better than CD-i Emulator in some cases. Starting the game from disc is recommended; this can be done with the built-in frontend by picking the specific game or through a soft reset after mounting the disc. It also has a libretro core, which makes it the easiest and the most stable method of emulating the CD-i currently. TinyCDi is an unofficial build of MESS from 2009 made by one of MAME's active developers, Haze. This build is named such that it only focuses on the CD-i. It uses a fixed game list, but it works better than the official MAME builds, especially with games like Zelda's Adventure for example. On the other hand, some games have more issues than they have on the official MAME build. But the same problem persists: There is nog Digital Video support.
The developer responsible for it is still involved with the project, although currently he's actually spending his time doing more arcade-side work. CD-i is still on a todo / to revisit list, it's just a rather scary task.
Ten years ago, MAME added basic CD-i support. Support for the Digital Video cartridge is planned, but first the CD-i developer is working on better understanding the system so that we can improve compatibility with regular titles. But after ten years, no real improvements have been made to the MAME CD-i emulation.
Plus they have literally zero documentation on how the DVC actually worked. There are rumors that some of them have a DSP56k to handle the MPEG audio decoding, but that still leaves a big black box where the MPEG video decoding is. It would also be nice to know how the presence of the DVC is detected, how the CD-i console itself sends data to the DVC to be decoded, and how the decoded results are then mixed with the output from the VDSC and such. Because all of that is a total unknown right now.
Our biggest hope on Digital Video CD-i emulation still lies in CD-i Emulator. With 0.53 beta 5 on the horizon, we might be seeing DVC CD-i titles on our laptop screen pretty soon!