Yup, just like Walmart pillow ticking and bore butter are traditional.
No matter what the shape, a conical in 58 caliber, the original point of this thread, is probably a lot more traditional than a 58 cal RB, at least in terms of numbers and varieties of 58 caliber guns from the time period, as well as number of shots fired. Heck, 58 cal minies sustained the civil war for the most part, and if a guy wants to use all lead conicals no sense pushing round balls on him.
I don't recall swaged round balls being used in period, so I guess anyone using them instead of cast is on your non-traditional list.
Here's a ponder point for you:
Is a guy using swaged round balls, walmart pillow ticking and bore butter traditional? Or is he disqualified from traditional by a guy casting his own round balls, using natural materials for patching, and making his own lubes from animal fat?
Gotta draw the line somewhere, and obviously we draw it in different places. I'm not going to criticize a guy having fun for not doing things my way. The point being, if he's using a sidelock muzzleloader and all lead projectiles, I don't really care what shape his lead is or whether he is using real black or a sub. He's welcome at my fire.