Dr. Craig is a liar.

[Esquilax]

Can they prove that they are transitional, in a repeatable demonstration?

That very much depends on how reasonable you're willing to be. If you will acknowledge that consistent observations we make in the present can be applied to things we observe about the past- if you accept, essentially, that uniformitarianism is a thing borne out by the available data- then I can and absolutely will make that argument for you.

If, on the other hand, you'll sink into solipsism, ignore all the evidence and assert that there's no way of knowing whether observable phenomena is consistently applicable to history despite there being no observable changes to the mechanisms therein, then I don't know how I could possibly demonstrate anything to you. You would, on this hand, be holding to a fundamentally unreasonable epistemological model.

So, which hand do you want?