The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
Estimated: Herzog & de Meuron's own project page gives 'Project 2009-2012, Realization 2012-2016', and Architizer and WorldArchitecture likewise give 2016, so the pin takes the end of 2016. Wikipedia's[3] 2017 completion year is the outlier; no source gives a day.
Something missing or wrong? Say it in your own words: a link that backs this pin up, a different start or end date and why, or a fact it lacks or gets wrong. The AI checks it against this pin's sources, searches for better ones, and adds any page that backs you up. The pin's own sources still count most. A picture that shows something else, or shows it badly, is looked at too, and moved down or replaced.