I cannot duplicate this. If I change a bank or cash account name, it is changed on every previous transaction, including inter account transfers.
I don’t know what you are referring to by this statement. You cannot edit the name of an account in an inter account transfer. You can only select other previously defined accounts. These are only selectable from a dropdown list. For example:
If you edit the name of a bank account, the edited name is what appears in the dropdown list, whether for new or existing transactions. I am on version 20.10.96, but this functionality has not changed in years.