From what I recall after chatting to Adrian around 2014, he couldn't get Elton to play on it because Elton was under contract to play with Yamaha-only pianos or something like that.
Had the pleasure of meeting Adrian around 2014 when he was showcasing his piano in Hamilton, NZ. All around a great guy (thanks for the birthday cake!). Still awed by how he pulled it off with essentially no experience!
Has there been any work on a model that can take in speech and outputs the phonemes (e.g. in IPA or an English format) similar to what Google's speech pronunciation tool, where it shows a "Sounds like you said ...."?