I ran into the same problem trying to make a skill give +5str +5fin -10int.
It doesn't actually scale with character level. There is a column called actpart under your stat_ that you created. It act like a multiplier to the attribute points, and possibly other stats. Set this number to 5 and then set your attributes, it will take some tuning, but the higher your actpart number, the higher your stats can go.
I believe in order for me to get +5 it was something like 9 under actpart and 7 for the stats.
