will the ball finish harder if it has a shinny surface compared to a duller finish?
Finishing at the correct angle to the pocket is more what bowlers are trying to do. Hit the four pins needed and they will knock down the other six. Hitting hard is about going off the pin deck the right way, with enough energy to shake up the pins hit by the ball and throwing them into each other.
Dull helps manage oily lanes, faster ball speed, less "hand" or the ability to turn and rotate the ball. Shiny helps manage energy loss, so on drier lanes, the ball can skid down the lane and have more energy left to hook and finish. Typically the shinier the ball is the more modest the reaction will be, but some pearl (or shinny hybrid) reactive resin coverstocks are very aggressive.
Thanks for your question.