In an application program development process, there are several phases for functional testing. Depending on the development process you adopt, the phases may be different, but basically there are two major phases to validate DBCS.
This phase test to validate the enabled DBCS functions for the product.
This phase is the final test to validate DBCS through out the system for the software product.
Translation Verification test can be performed separately from these functional testing so far as PII is well isolated from logic code, but should be done by the native national language speaker.