Back when the database was designed, some choices were made:
- The current year would be constantly updated to reflect the current status of your books.
- Past years (and abandoned books) are not updated, since this would slow down the plugin over the years, having more and more books to sync; not to mention rereadings, where the current date would not match past years.
- Read pages are stored as integers, not as a percentage of the total.
So, changing the page count only affects the main entry in the current year. Records are not updated because they reflect a moment in the past. The read pages in the current years' records
could be update if they were saved as a percentage, but that's not the case (and changing it at this point would be too much work for litle gain, since past years are not updated anyway).