@ManfredV said:
Good question. I didn't implement with Dorico in mind, and - not being a Dorico user - didn't try yet. The documentation doesn't say how Dorico communicates tuning information to its plugins, so I asked the Steinberg guys at the Audio Developer Conference. I'll update you when I hear back from them!
You do have other people on the VSL team who know Dorico quite well who you can check with. I believe by default with VST3 plugins it tries to use VST3 note expression to allow for individual detuning of notes. It can play back chords with quarter tone accidentals with the correct notes. To my knowledge this works in Dorico with other third party libraries and Halion-based libraries but not with Synchron player.
Quarter-tones in Dorico not playing back with Synchron Player has been an issue for a while apparently, and I would love to see this addressed.