All above sounds good & is probably true.
I recall about 1969 seeing at least one of these upside down & backwards flint pistols whilst shooting at Old Westmoreland Rifles, south of Pittsburgh, PA.
Got a friend from work interested, he normally shot 1911's. He bought whatever Italian percussion pistol was available at that time, with a zillion shallow grooves in it. Cast his balls of soft lead just like we all know is correct. Very poor accuracy. Being a .45ACP shooter, therefore too dumb to know better, he cast some bullets of hard lead, just like used in his .45. @!*%. Them there too hard balls, patched, took that shallow rifling.
Accuracy improved. Enough so, that being an accomplished .45 shooter, he beat $#*! out of the upside-down & backwards flint pistol. Don't recall whether they were ever happy to see him at a pistol match after that.
Upside-down & backwards is probably very good.
Practice is better.
Try honing your skills with an air pistol (rifled) in your basement at either 25 feet or 10 meters. Very humbling experience. Great practice, though, inexpensive & convenient.