JWs have such a low bar for what passes as proof that these statements make perfect sense to them.
The fact that anything at all happened in 1914 and they had pointed to the year beforehand, is to them astonishing proof of the accuracy of their predictions.
Just like any vague mention of a round earth in the Bible is astonishing proof that the Bible is scientific.
General prophecies about the destruction of various middle eastern cities are astonishing proofs that the Bible is inspired by God.
The fact that Bible writers appear sometimes to write unflattering things about themselves is astonishing proof of superhuman candour.
That you can build a loose narrative holding different parts of the Bible together is astonishing proof that God must be the ultimate author.
Assemblies involving thousands of people where litter is properly disposed is astonishing evidence that JWs are on the brink of forming a new world society.
And so on.
The only astonishing thing about most of the arguments JWs make for their various extraordinary claims is the incredibly low bar for proof they set themselves.