Even though he lived a long life that included World War 2 and nearly 30 years of Communist rule, I could locate none of his paintings dated outside the 1920s and early 1930s. In part this might be because the majority of his paintings seen on the web have no dates attached. Or maybe he painted less as time went by.
Schönberger painted in a composite of Modernist styles -- mostly Cubist, but with Fauvist coloring and perhaps a whiff of Futurism. So he was not especially "original." But to me this is no artistic crime. What's important, I think, is how well done paintings are in terms of how they look. As for Schönberger, even though I'm not much of a fan of Modernism, I find some of his works pleasing versions of that approach.
One more thing: Despite plenty of Cubist details, Schönberger's human figures did not stray far from normal proportions. This helps make his paintings more approachable to viewers indifferent to Modernism.
This is perhaps his nicest painting.
Much less Modernist, so I suspect that it was painted after 1935.
Another likely later work, judging by the subject's hair style.