You can use the title_template argument for that the default is “{{date.summary}}” but you can add any of the following variables in the string like that:
date.id
, date.summary
, date.description
, date.start
, date.end
, date.all_day
, date.transparent
, date.recurring
, date.location
, date.private
, date.created
, date.last_modified
, date.sequence
, date.recurrence_id
, date.attendee
, date.organizer
, date.categories
, date.floating
, date.status
, date.url
But parsing them with the generic ICS source sounds pretty bad, so it’s probably best to write a dedicated source for mzv Rotenburg
I wrote a source here: add Source for MZV Rotenburg Bebra by 5ila5 · Pull Request #3107 · mampfes/hacs_waste_collection_schedule · GitHub