As "The Rest Is Politics" podcasts points out, the meagre consequences mostly came to Brits: Ghislaine Maxwell, Prince Andrew aka Andrew Mountbatten, and the former UK embassador to the US.

Americans..?

Mandelson will probably rise again. After all, he survived the (consequences of) the Iraq war. Note that he got the job without an interview: https://www.bbc.co.uk/news/articles/cglg63n63wdo

Americans don't really do accountability all that much. People there who get to face the consequences are usually the ones that significantly harmed the financial interests of the very rich. Madoff, Holmes, Bankman. They operate more on a vengance than accountability system.