I doubt she's really in as much pain as she makes it look like. She's probably simply not used to handling any pain. If it was anything serious, she wouldn't be playing anymore, especially in the individual tournament later. I guess her finger just got twisted or squeezed a little. But it's just fine if it hurts the opponent's chances. Rion had an edge anyway with her beloved grandmother reading. She has probably heard her reading so many times she gains free milliseconds and is also extra motivated by it. She's so flawed a player that she'd need to develop fundamentally. I don't think winning a match despite the flaws would serve her well, no matter what the manager thinks.