I don't know if it should be like that.
For example when I'm having a dialog and have Persuasion option. I have +1 from proficiency and +2 from charisma. Success is at for example 10. I roll 8 and I'm at failure. Is the number on dice already dice roll+ my bonuses or what?
Yeah, the dice rolls needs to be changed.
As stated in this post:
http://forums.larian.com/ubbthreads.php?ubb=showflat&Number=682449&nt=19&page=1Dice rolls:these should have the bonus/penalty modifier added to the value of the dice rather than subtracted to the target. Apparently this is not just a subjective matter but contradicts the D&D rules that rolling a 1 is an automatic fail no matter what. 
