Thanks also for the numbers. I’m still a bit curious about how the automatch works. It doesn’t say in the faq/documentation whether the default setting is to use handicap stones or not.
What I would assume (and this could be way off) is that it ideally would like to pair you with someone of the exact same rank first if possible. If you are open to playing people of higher or lower rank it looks for those too (or afterward?).
Then for a pairing where one person has a preference for(against) handicap and one is set to default I would guess it goes with the opinionated persons preference of some(no) handicap stones or reduced komi etc. If neither player has selected a preference, I wonder how it handles that case.
Edit: I guess this is a partial answer in something you linked where in one case it is not the default for people with high deviation in ranking