Is there another way to copy the calendar from my iPad or my new Apple MacBook Air back to my older MacBook Pro?----when iPad and Mac are signed in with same Apple ID and password on the same network , when deleted calendar and events are stored in Mac and in iCloud.com they will be synced with iPad see the article https://support.apple.com/en-in/HT202337
It does look like it's stored a calendar today and I made changes (on the MacBook Air today), so maybe it won't save a blank calendar? ===restore of calendar will take time , depends how much is the data , when it is restored a mail always appears from iCloud server in IMAP account , if Apple ID is set up in mail accounts .
Only the MacBook Pro deleted it because I ran a cleaning program on it. ------don't use any cleaning apps on Mac , in finder > applications , if you have installed them right click over it and move to bin , restart the Mac and empty the trash , unknown apps will corrupt Mac system files , you can consult about it with senior apple care advisors in brief see the link https://support.apple.com/en-in/HT201232