The triplane ,with a dying pilot, landed roughly and after running a short distance then flipped up on its nose. Richtofen's body jackknifed (only lap straps at that time)and his face hit the gun butts, smashing it up nastily, as is evident in the post -mortem photographs . I think these were published in Dale Titler's "The Day the Red Baron Died". For a number of reasons I do not think he survived the landing post the nose hitting the ground.
As to how much of his body was actually re-interred to Germany is another matter that was investigated by Titler with surprising results. Read the book!