Hazel 5 will not access the calendar via Apple script

I am trying to set up a Hazel rule to file away receipts from my library in DevonThink 3 while creating a calendar event when I have to return the books to the library.

The recognition of the dates works fine as well as filing in DT3. The problem I am facing right now is that I can’t access the calendar for creating a new event with the date of return, that Hazel already knows.

I hope someone has some recommendations on that, I am stuck.

Also, in the settings in Big Sur I saw that there is a setting Privacy->Automation where Hazel and Hazelhelper have access to DT3 but the calendar is not listed (and cannot be added as well).

So here my two questions:
If this problem is privacy related, how can I fix this setting in Big Sur?
Is my script otherwise correct? I am not sure about the correct syntax for forwarding the correct date to the calendar event…