Hard to know for sure, he was still having issues earlier in the fall. He missed a lot of Europa League because of it.
I don't know what Speedy has to say on the subject, but I remember one of the issues with Ronaldo was that he was so explosive that his knees and hamstrings took damage during the sudden starts and stops. Smith-Rowe is a fairly big lad who ticks like a heartbeat on the pitch. He's listed as 1.82 but I'm almost sure he has grown a few centimeters since then, and I don't think he has ever run in a straight line in his life. It's all sudden tempo changes and quick dribbles and switching directions and accelerating past opponents. Players who play like that are usually smaller or leaner in my personal observation.
He does seem to be alright as long as he maintains peak fitness, but I think he'll have to be carefully managed throughout his career. Hopefully he'll never have to spend 6 months nursing a bad hamstring ever again.