Help! Need to Replace Corrupted iCloud Sync

Syncing my iPhone and iPad results in corrupted playlists (hundreds of different duplicates), the result of a sync gone wrong a long time ago. Trying to edit them would take weeks.

My mac music app has a non-synced good copy of the playlists. If I try to sync the mac copy, it gets corrupted, too. I think it gets merged with the corrupted copy, which makes it even more corrupt. But I can replace the mac music library with a good copy that was saved before the corruption. All devices have the same appleID.

How can I get the good mac copy out to iCloud and synced to the iOS devices?