The disagreement comes from what the receiver started as. It started as a rifle receiver, and was modified (either in czech or the US, doesn't matter which) into a handgun.
Thus, any and all magazines are designed initially as rifles mags. For your to get your pistol mags through, you'll need to get a purpose built handgun receiver and go from there. Not convert a intended rifle receiver into a handgun "configuration.
Interestingly enough, a new receiver in the form of the 958 is being made by wolverine and is going through classification. So new 58 style receivers are in the works.
Make a handgun receiver right from forging, and then you'll have what you need.
Converting a rifle receiver vs forging a handgun receiver is the key issue. XCR and AR receivers for example are forged as "pistol" roll marked from the factory. They are designed, from the preforging process as pistol receivers. There in lay the difference in the lab's eyes.
Until then, they are all considered rifle mags designed for rifle receivers.