The acid test of science is whether other people can repeat an experiment or observation using the same equipment. Thus we know all that school chemistry. physics and biology stuff to be true because we have all proven it over and again for ourselves.
Now, if someone builds and exact replica of the Pearse monstrosity and flys the contraption 1,000 yards there would be grounds for crediting all the claims.
Many Wright Flyer replicas have been built and flown. The body of evidence (and our lawyer friend will agree that even in the most cut and dried of cases there is some degree on contradiction - it is the weight of evidence that counts) the body of evidence pushes the Wright's acheivements up there with great genius.
The one difference with Pearse is that no picture was taken... no, hang on, the two differences were that no picture was taken and the witnesses disagreed... no, wait a minute, the three differences were that there was no picture, no contemporary witness account, no flight instruments...