The "Display Name" field for aliases should be backed up into the CSV file that gets produced when going to Alias import/export -> Export Aliases under Settings.

At present, notes entered under "Alias Description" are included, but Display Names are absent.

The Display Name field allows for custom per-alias user entered names that should certainly be preserved in backups, and restored in the event that the CSV file gets used "for a future batch import" -- which is one of its explicitly stated purposes.

At present, my manual workaround is to ensure that custom Display Names are also copied and pasted into the Description fields for their respective aliases, so that they at least get backed up in some fashion.