But it IS a flaw. It is pretty much the definition of what a flaw is!
Again: my post was not a complaint. I never demanded for the flaw to be remedied and I don’t even care if the game was annulled. I just wanted to understand how they did it and how to counter it. So no need to console me and explain that it will keep happening. I don’t really care. If we were competing for some sort of a a prize, then it would matter. But we don’t, it doesn’t happen often, and even if it did it would only affect my ranking.
Usually I block players who annoy me with “disconnection’
(That is another idiotic and also absolutely pointless trick that is much more common and much more annoying: the opponent appears “disconnected”, but when you check their profile you realize they started another game. I reported and blocked many of those. But I also wonder how they do it.)
I didn’t even block this score cheater because I was actually curious about them; if they’ll do it again, how they do it, whatever else they’ll do and who they might be demographically speaking. For some reasons I think that it is likely a teenager and more likely male. 
So this thread was never meant to be a complaint or criticism, and starting it I was not irritated. I was curious and rather amused. I was only maybe a bit annoyed with myself for not being able to prevent it the second time. Because I did expect they would do it. But I found it rather funny and stimulating, it broke the routine.
What seriously irritated me was that people kept misinterpreting my impeccably articulated report and questions: poor reading/understanding skills. And you did worst on that one. Everything was in the post, the whole story, and you couldn’t miss any comments because there was never any need to read any.
Now:
Your account of the second game surprises me. I do usually look at the score prior to approving it, except for when I clearly lost maybe. Too much time has passed now so I can’t be certain what had happened. But I am actually pretty sure that I approved the correct score. My most post says so and I trust myself to be accurate.
I guess the only way for me to learn that trick and how to counter it is to open a second account, challenge myself to a game and try cheating the score.
I am not sure if I completely understand why the flaw can’t be remedied. But I take your word for it.
What I wonder is why the function is even necessary. In the 2000 games I’ve played I haven’t encountered a situation where I felt that the initial score was incorrect.
But, if I play around with that function, I might at least figure out how it works and why it can’t be improved.
Thank you for looking at the logs! You don’t need to concern yourself with this any further, not for my sake anyway.