restoring calendar data from old mac

As per this article : Calendar for Mac: Import or export calendars

To share or back up a calendar that’s in the On My Mac section of the calendar list, you can export the calendar’s events, then import them into another calendar or to another computer.

If you use a calendar account, such as iCloud or Exchange, you don’t need to export and import its calendars to back them up or have them appear on your other devices. The account calendars are stored on the calendar service provider’s servers, and are automatically updated on all your devices set up for the same calendar account.

You can read the complete article .

Not sure if the following are "brilliant ideas" but I would start by removing the 2 files with .icbu endings — these are backup Calendar archives that should not, IMHO, be in the this Calendars folder. Anyway, they´re nearly a year old!

I would then drag the old Calendars folder to your new Mac´s desktop, then open ~/Library/Calendars folder on your new Max and drag the contents of your old Calendars folder into it. In other words don´t replace the whole folder on your new Mac, just replace its contents! And Calendars should not be open and running when you´re doing all the above! (I´ve been able to restore my Calendars data by doing this, albeit on a healthy HD from a Time Machine backup on an external drive.)

Now re-boot your new Mac and open Calendars and see if this has worked.

You don´t mention if you´ve turned on iCloud Calendar syncing — if so, you´ll probably have to log into iCloud again on your new Mac! Also, did you have a Time Machine backup of your old Mac? You could try going back a few days to a date when your old Mac was working OK and restoring the Calendars folder. It could be that with HD malfunctions/dying some system files/folders have become corrupted. Hope at least some of the above can help you! Cheers, Ian.

Have you tried a restart?

You could sync your calendars with iCloud and they will download to the new Mac.