It is quite special that a 2-stage ko has a local tally of 3, which is due to White yielding the ko (the page says so) effectively Black wins the second ko without ignoring a ko threat. This is may be sth. worth pointing out, that kos which you end yielding without compensation (sente ko?) are hard to fight.
This series is a wonderful christmas present.
I'm happy you like the series. In the midst of all the terminology turmoil, it was a way for me to peacefully add value to the library and understand a few things better myself.