Why do Germans get so wrapped around the axle about proof house certifications and have such a fear of guns blowing up in their faces when using anything over half of service loads?
Even with the India guns, blowups are extremely rare.
Passing a government proof house test is not even close to a guarantee that a muzzleloader will never split the barrel with even a weak load. Not fully seating a bullet or ball, or any kind of substantial bore obstruction will ring or split a barrel almost every time, and rarely causes serious injury.
I own, and have owned many muzzleloaders over the years, not one of which was proofed as far as I know, shooting all kinds of loads, and have never had a problem.
Just load the thing with 30 to 50 grains for starters and go for it.