I'm in the process of testing out a few book sites beyond GR like Hardcover and Storygraph. In doing so, I'm adding a lot of books I've previously read all at once. I'm ready to try and build that master list of EVERYTHING I'VE READ, the one list to rule them all. The problem is that this makes my stats really weird, but when I go in to each book to try and label when I read it, a complete specific date is required for both start and finish. If there could be a simple checkbox for "in the past" that would get treated for stat purposes as a specific yet indeterminate date separate from actual dates, this might solve the problem. I'll add that my books weren't properly labelled in GR, so everything I imported says I read it in 2011, but everything I've added manually doesn't show up in any stats because there's no date associated with it. And when I know I read a book like last year or two years ago, I'm kind of forced to make up a date range which takes both a lot of clicking and mental energy. So I'm not sure if it could work with your current stat system to have a few additional date options, like "in the past" and also a vague "YYYY" for the general year I read something without specific reading dates beyond that.
//thanks!