Trying to analyse my defeat, 7.e18 was an error. I saw quickly afterwards how nice could be 8.i13 for black, both blocking an f10 attack from h15 and threatening f16 with i19. Then I was not able to come back in the game, and I still don't know how I could have done.
I wouldn't say that 9.r14 is not "serious" but it would allow black to take an advantage on the top such as 10.p8, then 11.p1012.q10 or 11.o912.p12
One of the way you can take advantage is to exploit a move which is not balanced enough... If you can make the opponent to play such a move, then you can attack on the weaker side, and hope to keep your advantage till the end.
Anyway, imho the key point in this game is that |7.r16 would have opened a second path the bottom for white... and instead of that, |8.i13 has consolided a second path to the left for black.
Seems that it would have been better to answer |7.r16, then something like
8.p12 9.j16 (10.k18 11.n16) or (10.l14 11.f10)
or
8.o15 9.s13 10.q14 11.r11 12.r17 13.s18
I wouldn't say that 9.r14 is not "serious" but it would allow black to take an advantage on the top such as 10.p8, then 11.p10 12.q10 or 11.o9 12.p12
One of the way you can take advantage is to exploit a move which is not balanced enough... If you can make the opponent to play such a move, then you can attack on the weaker side, and hope to keep your advantage till the end.
Anyway, imho the key point in this game is that |7.r16 would have opened a second path the bottom for white... and instead of that, |8.i13 has consolided a second path to the left for black.