macOS Ventura - Contacts App fails to import .abbu with Lists (Groups)

I have over 9,300 contacts, and 100's of Lists (Groups). Many are messed up after allowing Outlook App to connect to iCloud Account, resulting in strings of code added to contact fields including:

X-ABShowAs:COMPANY

Item2.X-ABLabel:_$!%3CHomePage%3E!$_X-ABShowAs:COMPANY

item1.X-ABADR

item1.X-ABLabel

Prior to allowing Outlook to connect, I had manually backed up my Contacts > Export > .abbu file

so was hoping to import them into a new temporary user account and then get them syncing back to my main iCloud account and clearing out the current contacts... So far I have tried...

Account (Main) > Contacts App > Export > .abbu with Lists (Groups) = Success

Account (Blank, iCloud Off) > Contacts App > Import > .abbu with Lists (Groups) = Fails

I can see Library > Application Support > AddressBook does contain the imported files but Conacts App not displaying them > Only blank/empty Contacts App after completing the import, so I don't understand why the App does not read and display the content. Logging out and back into user account does not help.

Have tried to open package contents and manually copying over the contents, but makes no difference.

Many Apple discussion posts over past 10+ years saying Contacts App happily exports .abbu files, but never able to import them. A quick test of exporting and then importing straight into another test user account shows that within same OS, import feature does not work.

Looking for others on hear to help with steps/files/filepaths to manually copy the contents of the .abbu file in a way that the Contacts App will actually display the copied content (Contacts + Lists (Groups). Just contacts is not enough, I need to restore the Lists (Groups) as well. Hoping Apple engineers will help me after Level 2 Support asks them to step in.