I was playing a game here:
and I had one misclick at move 211. I actually changed my trackpad settings yesterday to tap to click (since changed back). I was winning pretty handily so I acknowledged it, but didn’t request undo. I was shocked in review though to see that it was a difference of about 20 points! I’ve been thinking about end game recently, but I think this is the clearest example I’ve seen about how much end game moves can be worth
The difference of score before and after your misclick was 26 points → 18 points - enough to win comfortably. I think your descent to E19 in move 214 is what made the game close. But yeah, I agree that end game can change the outcome score significantly. You only win after the last stone is laid.
In this game, I too made severe end game mistake 
. I thought I’m winning after all territory on the board sealed off, then my opponent started cutting me off everywhere starting with move 235.