I can’t say that I’ve had any issues with Thunderbird, other than reconfiguring hotkeys is a pain.

There is a caldav addon that allows syncing with remote calendars. I use that to coordinate calendars on my computers and iphone.

Notes longstanding problems, but isn't aware of calendar feature that has been around for a decade?

Thunderbird had some big hi changes over that time, you might like it.

To be honest, outlook for mac isn’t particularly great either. It is not much of a step up from outlook web access, which is what I ended up using on linux after trying all the mail clients. Evolution with the ews plugin came close, but required a ton of configuration and the tasks integration was never quite right.