Solved
How to customize the default label of adding records for an OOTB Data Type in Pega Constellation?
I'm using the Account list page list property, which is already available in the Customer Account data type of the Pega Constellation common data model. As a result, the default label "+ Add Customer account" appears for the table view, as shown in the image below.

Is there a way to customise this label, for example, change it to "+ Account" instead?

With the latest Pega Constellation updates, there's now a direct way to add a custom "Add" label for a data type. For example, in the screenshot provided below, the data type is Request Type, but the custom "Add" label is set to Payment.