More macOS CalDAV ridiculousness

I’m curious as to if anyone’s managed to get Apple’s Calendar.app syncing with a self-signed certificate?

After going through these links (among others) I’ve been able to get Contacts.app syncing:

(Touch wood I can keep it working)

I’m still getting the “unable to verify” error in Internet Accounts when trying to set up a CalDAV account.

I’ve been able to get two 3rd party apps syncing fine, so the issue’s definitely on Apple’s end. Just wanted to see what everyone else is doing here and if there’s something I may’ve missed.

Thanks so much for any input.