I know android has API for creating new calendar. So events, which are created in that new calendar, can be protected not to be edited.
But what about calendar reminders. They doesn't have functionality calendar events have.
So each calendar event has parameter - calendar Id. So I can create new calendar with unique calendar Id.
I created new account and then new calendar from that account.
Calendar permissions can be set when calendar is being created.
Calendar reminders has only 3 filed can be filled in. They are Event Id, time in minutes and alarm method.
So everyone can edit reminders for protected(read-only) calendar events.
I have not solve that problem.
I hope in future multi-account functionality will be added to calendar reminders too.