Hinted here, the new version of MAME was planned to have new CD-i updates and improved compatibility in version 0.240. That version was released today. You can download it here. Ryan Holtz comments on the CD-i part: "Building on the work last month, the CD-i has received a few more fixes that improve performance and add support for more discs. In cdicdic: we fixed the audio crackling, and fixed various hangs, together with CD-i Fan]. We made significant updates to the CD-i driver." Without the help of CD-i Fan, who is the author of the other main CD-i Emulator, aptly named CD-i Emulator, this update would probably not have been possible. As by the looks of it, this will probably be the last CD-i update for a while now.
[Thanks, MoogleGuy, CD-i Fan]