Whose job is it to review pageviews and update the definition when
issues are found?

I see the thread evolved a bit today. But I'll note this for people going through the archives:

There seem to be a few levels of review of pageviews. There's been stuff for the monthly metrics meetings (e.g., earlier this month Kevin Leduc ran some reporting). Tilman Bayer is also working on some regular reports for Reading; he has generated quarterly scorecards around this sort of data in the past, too. Reading is a customer of the data so to speak. I think a lot of us are doing ad hoc lookups from time to time.

For reporting issues my working understanding is if someone notices an issue we should submit a bug against #analytics in Phabricator, with Analytics implementing updates as needed (as Oliver noted in a later report, how to systematize review is a question he and Joseph will look to answer).