Please, excuse my ignorance. I never used the Gibberlings Tweaks, so I don't know what's inside.
Does the sentence I quoted mean that the code modding is outside the scope of this project?
The problem is: I was always disappointed by the fact that IWD2 does not use HPCONBON.2DA rule table which means there's no easy way to implement CONstitution-based HP-regeneration.
HP-regen is my personal fetish, which lead me to dislike the game without it, 'cause I don't feel like the sleeping without a camp after every couple of battles is the way a group of real adventurers would go.
Some days ago I decided to implement regeneration the hard way, and found a bug during this research.
It resides in the function (sub_542a90 in GOG version):
CRuleTables::RollHitPoints(int nSides, int nRolls, int nLevel, int nMinRoll, int nModifier)
This method is called on level-ups to roll for hit points. When the roll result is less then nMinRoll, the nMinRoll value is used.
But when it is greater, then the die is rerolled, and the new value is used indiscriminately, instead of just using the old value.
This means that the HP value rolled on level-ups tend to be lesser than average, and can even be less than nMinRoll.
For player characters nMinRoll usually equals 1, which makes HP roll of 1 more probable than all the other values.