It seems that Syrinscape does not properly handle URI scheme that advertises on a macOS. If one copies link from the app, say:
syrinscape-fantasy:elements/YnVnYmVhci1iYXR0bGU6Om1hZ2ljLW1pc3NpbGUtYS1jb3B5/play/
and then type in terminal:
open syrinscape-fantasy:elements/YnVnYmVhci1iYXR0bGU6Om1hZ2ljLW1pc3NpbGUtYS1jb3B5/play/
it does nothong.
I tries to use and app to associate custom URI scheme with Syrinscape (SwiftDefaultApps), but is seems that URI is passed down to the Syrinscape App and ignored.