Although there is not a lot of KPIs being reviewed, the fact that the MSA is reviewed annually shows they are constantly looking out for increasing risks in modern society.

"This statement has been approved by the organisation’s board of directors who will review and update it annually." This can be found at the bottom of the statement where the CEO signs it.

although there isn't explicit detail on KPI's grace is correct to point out that the annual update means they are always looking out for risks of modern slavery