How can you map two different CDTs (a basic one and another with all the columns

You don't need anything special as long as they have different names and they both use the @Table(name="") annotation to make it point to the same table.

Let's say that CDT A has two fields while CDT B has the 4 fields/columns the table has, for Appian this is transparent if the @Table annotation is telling it to point to this table since CDT A matches the table (because the table contains the two columns mapped to the CDT fields)

You don't need anything special as long as they have different names and they both use the @Table(name="") annotation to make it point to the same table.

Let's say that CDT A has two fields while CDT B has the 4 fields/columns the table has, for Appian this is transparent if the @Table annotation is telling it to point to this table since CDT A matches the table (because the table contains the two columns mapped to the CDT fields)