Faulty ICal search function and random overpopulation of events in syncing

Since purchasing a brand new Imac and operating on Sonoma 14.4.1 I have had an incredibly difficult time with ICal. When syncing with my Iphone, quadruple (and more) populating of repeating events - eg a weekly event became daily, yearly event became daily). After considerable consultation, no-one seemed to be able to help. Then the search function was erratic and unreliable. I have rebuilt the Spotlight several times. Presently, the search will only bring up future events, even when immediate past events are clearly visible. Have had other issues with other programmes and am almost ready to ditch Macs completely!