Update "Account_CUSTOMPROPERTY40.ATTESTATIONS" from User Interface Branding Configuration
In Certifications, account level customization for attributes are not driven from the endpoints but from the details in the Saviynt central property file, which you should be able to update from the UI by managing labels from Admin > Settings > User Interface Branding Configuration
Use the names that start with Account_CUSTOMPROPERTY* for e.g Account_CUSTOMPROPERTY40.ATTESTATIONS to update the Account Custom Property 40
One thing to note is that this change will end up re-naming the CP10 for all applications in the certification. Now this may not necessarily reflect the actual value that you may have configured at the endpoint level for e.g. in your AD endpoint your Account CP 10 could be ObjectGuid while for AzureAD the same attribute could be UPN.