What?

He removed corruption from the Klingon government after becoming Chancellor, and held the job for at least 5 years and was well regarded.. circa 2380.

The Klingon Empire continued for another 600 years until The Burn in the 31st century.

What kind of measure of success is this? A political action has to endure for all time or it failed?

Nb: for those of us who don't enjoy Kurtzman Trek and dismiss it, its still going.