Thinking about my earlier reply, I keep wondering whether in 1922 the newly formed Czech Army had any Hungarian speaking regiments. If so, it would explain the curious aspects of the uniforms.
If your great-uncle still lived in Dunaszerdahely, which in 1922, was part of Czechoslovakia. (Dunajska Streda) then he would have been called up for the Czech army, presumably at 18.
If, however, he lived in Hungary, or was keen to make his career in the Hungarian military he may have joined the Hungarian army.