I have the same problem with the Schedule component.
When I set locale="cs" to the component, I get the abovementioned error.
I can confirm that cldr data are loaded correctly in the app when the component is being instantiated. But somehow the component doesn't see the globally loaded cldr or L10n data.
Could you please share the solution to this problem? I've encountered it on various version of the schedule package, on Angular 7 and 8.