Thx RedPython.
@EvilSmoothie & @AMD, I apologize because I answered without taking the time to study the case of titans. But finally I did it, and the weak point of the titans causes critical hits identical to the others (damage x2).
And thank you for spurring me! Because it highlighted new points:
Titans have much more unbalanced stats than heroes (for example, Att~1020 and Def~420 for a 5* Demon Lord). Or, their damage is not calculated as for the heroes.
Tiles can perform critical hits outside the weak spot.
Powerful colors on the weak point make x4 damage.
Critical hits on the weak point cancel out color weakness (for example, a green tile on the weak point of a red titan does x2 damage, not x2/2=x1 damage).
And here is a new job to do! I do not have enough data to check if this is also the case for all critical hits. Iām going to run a red team on 8.7 to check this point.