EventKit genuinely doesn't expose sections (or their subsets/groups). The only working approach I've found is to bridge to the Reminders SQLite store and handle the CloudKit sync manually, which took some reverse-engineering of how remindd works. I documented what I learned while building remi (https://github.com/mattheworiordan/remi), a CLI for Reminders: https://github.com/mattheworiordan/remi/blob/main/docs/APPLE_REMINDERS_INTERNALS.md