That's great news Joe - well done.
As others have said, Private Eye has a high readership amongst the establishment (partly because they're worried they might appear in it). You can be certain that the Charity Commissioners will be aware of this article and will want to do a thorough job on the WT's abuse problems knowing that the Eye's spotlight is on them.
Like you, I was surprised at the extent of the data request. No timeframe was mentioned but going back a few years I bet there are many skeletons lurking in the WT closet.
The headline was good and may be picked up by the popular press ('Silent Witness' is a popular BBC crime drama in the UK).