You can create mneumonic tables in Signal Tap, but those are meant to decode "parallel" signals (i.e. the seven separate signals that make up a 7-segment display) as opposed to decoding serialized data like what you show here. Signal Tap can't do that. It only looks at captured data one clock cycle/sample at a time.
We do not receive any response from you to the previous question/reply/answer that I have provided, thus I will put this case to close pending. Please post a response in the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support. The community users will be able to help you with your follow-up questions.