US companies have plenty of avenues for appeal in India. They have used those avenues more than once and successfully so. If they knew of corruption, they would have raised it and everyone from the media to opposition political parties would have jumped on it.
I’ve seen on Livefist allegations from a supposedly reputable source on corruption involving people close to Dassault and the Indian govt. Dunno how accurate, but wouldn’t surprise me. Even then, Rafale was probably always going to win this contest.