There is
a mod that tries to increase difficulty, but with the lack of tools right now, the best they can do is change AC/saves, attack rolls, and HP.
They really need to add more mobs too, so there is more shit coming at you, and AoE is more rewarding, but it is the early stage for mods, and as more people develop off of each other, there will probably be some amazing stuff in a year+.
It's weird that you replayed BG2 some times, with mods, and haven't played any of the Pathfinder games. Since they are still the closest anyone has come to the infinity engine games.