Must something be credible to be reliable?
How can one rationally say that they can divorce the concept of truth from the concepts of either reliability or credibility?
Challenge: try saying something reliable about a readily observable phenomenon that must not at the same time be truthful to make it credible.
Next Challenge: try saying something false which debunks fraud.
the past is not a readily observable phenomenon. Biology and geology have large branches devoted to history. These cannot ever produce an absolute, complete and final truth.
What they attempt is the kind and quality of investigation seen in a first rate criminal investigation, a reconstruction of the important features of the past that can survive any new evidence. Each new piece of evidence that is consistent with the reconstruction adds to its credibility.