With Raphinha, it's important to understand when you evaluate him that Xavi is implementing a totally different system than what we usually see at Barca or have seen ever at Barca.
Off the ball work is becoming just as important as on the ball and the most important facet of our game is the high press and intensity, which is a form of defense but also a form of offense that creates big chances, winning the ball back in high areas.
Considering this you have to look at Raphinha in that light also, where he has indeed been very good off the ball, working hard and pressing with intensity. He is also fast enough to regularly stretch the opponents defense with runs but sometimes struggles on the final dribble, where Dembele succeeds.
I would keep him for now and let him adapt/grow, his performances haven't been bad enough that he is losing value and I quite like him.