I suspect that since the cartridge in questions seems to be some form of 9 x 23 mm round, and made from a .223 case, that it probably was intended for something where ammo wasn’t found too easily, like 9 x 23 mm Bergmann-Bayard, or 9 mm Steyr. The former is available thru 9 mm Largo surpolus and the latter thru Fiocchi, but neither are found everywhere, and some shooters are not aware that the 9 mm Largo is the same as 9 mm Bergmann-Bayard.
The .223 is too small in the base, but being a high-pressure rifle cartridge, the case base and head are very strong, and despite being undersized and therefore unsupported in 9 x 23 mm chambers, the cases will hold the pressure. There might be realy extraction problems in a .38 ACP or Super, when you combine the undersized 5.56 case and the fact that the .38 ACP/Super is semi-Rimmed. Successful .30 Mauser (7.63 x 25 mm Mauser) has been made in the past from 5.56 cases, so probably a 9 x 23 mm could be as well.
With great companies like Starline supplying brass for about everything these days, using substitute cases to make these rounds is pretty much an exercise in futility in my view, but people still do it to save a dime.