Look, I'm not a handloader, but as I understand it, the primary function of the cartridge case is to act as a gasket in order to seal the breech of a breech-loading firearm. The thing that really has to stand up to the pressure of the fired cartridge is the firing chamber, as Duvel points out. Sure, the brass has to hold up, but if the firing chamber bursts, the brass hasn't got a chance, even with a load well below maximum.
It's like what I read once about hot-rodding engines - the problem isn't getting the engine to produce more power, it's getting the engine to hold together under the increased output.
So hardly anyone is going to want to fool with what the OP describes, because if you load it the wrong gun, it's good-bye gun, and maybe some fingers too.
Yes, I know that this is exactly what the people who developed 357 Magnum and 44 Magnum did - but they did so in the process of inventing 357 Magnum and 44 Magnum. 9x23 Winchester already exists, so what's the point? If you want to shoot 9x23 loads, it would be a lot safer to get a 9x23 gun, IMO.
You might also want to read up on something called "Super Face", which was a thing that happened before 9x23, when people were hot-rodding 38 Super for competition shooting.
Finally - and as I said, I'm not a handloader - isn't 9x19 what is called "case limited"? That is, it hasn't got the case capacity to be loaded a whole lot hotter? If that's true, wouldn't shortening 9x23 brass to 9x19 be a step backward? If 9x23 brass is thicker to withstand greater pressure, wouldn't it actually have less capacity than standard 9x19 brass once you shortened it?