Raphinha is not naturally a left winger. In fact, last season he didn't even play the left wing. It was like that on paper, but on the field, he usually drifts to the middle and has almost a free role on the field. He could totally play the free role because he had to maintain the flank. With Nico in the team, Raphinha can play behind the striker and have a freer role on the pitch. He can also act as a second option to Yamal's position, which is his natural position. I don't see an issue here at all.
I know Raphinha plays as a left winger for Barca, but just to be certain, he's played different roles in other clubs he's been in. I did a quick search, and I found out that he can also play as a right winger and an attacking midfielder. That's good, as it will give Barça options in case any of the attacking players get injured, he can easily make a switch. Also, I think he'll make a good striker, though I'm not sure he's played in that role.