I have never heard of "Java TCKs" but after a little research, I understand them better. Just out of curiosity, what would passing the Java TCKs do for me or my users?
Certification will lead to the recognition of your product as an enterprise-ready technology, allowing interoperability and intercompatibilitization with all Oracle Java products and libraries. In today's complex and increasingly specialized economy, a promise of compatibility is not sufficient. The Oracle Java Compatibility Process™ provide you with the credentials you need to succeed in acquiring market share.