What is the meaning of 'Umar's statement: "What a good innovation"?

Question:
Regarding innovations: some people cite the words of 'Umar (may Allah be pleased with him) when he gathered the Companions for the tarawih prayer and said: "What a good innovation"!

Answer:
This is from the linguistic perspective; it is an innovation in terms of language, whereas in reality it is a sunnah (recommended practice) that the Prophet (peace and blessings be upon him) performed, legislated, and called people to. However, the Messenger (peace and blessings be upon him) passed away without gathering them under a single imam, so 'Umar introduced this, gathering them and calling it an innovation in terms of language—the language of the Arabs—not in terms of the Shari'ah.
Q: Is the argument of the one who cites this invalid?
A: Even if we concede that 'Umar said that, 'Umar is not infallible; 'Umar is one of the Companions and is not a proof in the words of Allah and His Messenger. However, 'Umar's words are to be understood as referring to something good, so that no bad opinion is formed about him.