Yes it is tight but I think that against a good player (that plays tight 3Bet strategy of only 12% from the SB) it is ok to be tight. I made sure to include positional etc advantages when creating this chart as I used the solver to come up with the EV that is realized when starting stack is 100BB.

Be aware that the 3Bet is actually more then 4x as I assumes a raise of 2.24 and a 3Bet of 10. This ofc makes that one has to be slightly tighter then against a real 4x sizing.

When the 3Bet is truly 4x and the bet was 2.5 one will see that KTs becomes an almost 100% call (real EV is 7.57) and that K9s becomes close.

It depends heavily on what range you give villain. But once you give villain the described 12% 3 bet range. Then AQo and KQo aren't +EV calls so I did put them in the 4bet bluffing range as they block a lot of 4bet calling range (don't think villain should have a wide OOP 4bet calling range so blocking 5 bets becomes important) and of the 5 bet for value range.

My doubt is that you are thinking about the best exploitative preflop strategy taking into account the EV then generated by a postflop GTO solution (which does not happen in the pool). Could a better adjustment be made on the opening range rather than on the defense range vs 3bet?

If SB is only betting 12% and if the BB defends 'normal' yes then I would open wider. But that is besides the point of the study I want to know what the best defense against a SB is who defends with 12% of 3Bets which is way to low.