additional author cloud but values correspond to no. of pages rather than no. of books

I would much rather see authors listed by total page count than books read

But how would one determine the "page count"? Particularly with authors whose works are in the public domain, there will be many editions with wildly varying page counts. And how would you figure in ebook and audiobook editions?

Presumably you'd go with the page counts in the user's cataogues. You could default to "green" ones if specific ones are missing, but the sort of person who cares about the accuracy of such a cloud is probably one who makes sure their books have accuracte page counts entered.

(I dunno how you'd treat multi-author books, however. If you have an anthology with an editor and nine contributors, they're unlikely to be responsible for one tenth of the page count each.)

A very interesting idea, but it seems impractical from a number of perspectives.