Calendars no longer synch through Finder in Ventura

Around August 2024 a Ventura update stopped Calendars from synching through Finder. Apple support troubleshooted for many months (including wiping iMAC and reinstalling Ventura - Calendars still didn't synch even before my data was restored) but threw in the towel today and suggested I try here. Don't want to use iCloud. Anyone got a workaround or solution? iPhone 16Pro and 7 year old 27" iMAC.