Hello. This is Klaytn API Service team.
Please refer to the following information regarding maintaining your private key.
When migrating an account, you will also have to create a new private key, meaning that you will no longer be able to use the existing one. In the case of KAS, users are not able to view the private key because they are not revealed in plain text. Therefore, it is impossible to maintain the private key after migrating the account.
If you want to find out more about the Wallet Key management mechanism, please check out What is the Mechanism of Safe Wallet Key Management post on Help Center.
Klaytn API Service team.