In my experience wisdom isn't a blanket coverage and it always comes in "degrees" or "levels". A shooter/builder/historian will ultimately know a lot about a spot here, a spot there and nothing really about this area over here. It takes long (more or less) experience for someone/anyone to earn a good grasp of "what makes a good flint", the best powder for a job, where to shoot deer, not to mention ball size, patch material, lube, you name it. Most of what is offered as advice is merely "opinion" and is normally no better or worse than than advice from someone with less experience. Really, now, experts - as commonly understood - DO NOT EXIST when it comes to the ins and outs of muzzleloading. There are pretty good authorities on styles, history, etc. But they know very little more, if that, about the other aspects than the guy who's been into the sport only 5 or 10 years. Think PhD - Pile it Higher and Deeper. Or think of it as learning more and more about less and less. I have my area of expertise, but I'm no expert. Despite the degrees, academic and otherwise, it would be foolish for me to claim to be an expert on anything. There have been a few (very) "renaissance men", but none, I'm sure, writing about muzzleloaders.
Okay, so we have no experts; only certain individuals who know a lot about certain little things. What about celebrated gun builders and the art they produce? Well, they ARE incredibly knowledgeable about anything to do with gun building; but they seldom agree with one another, hhhmmm... Other than that, well, they are about like the rest of us. Certain laws of physics/chemistry are, as far as we know, immutable. These can be a basis for a "pretty sure this is right". Different strokes for different folks and if it works for you it's some degree of right, guaranteed.