In Polish, we use the adjective "polski" for anything that is made in Poland, too, despite of the origin of the idea of the product.
You'd be better to say "Heinz products are made in Poland for the Polish market" to avoid confusion.
But yes, you're right - in English, just because it's made in Poland, doesn't make it Polish. For instance, VW cars are most definitely German - Polish-built, but the products themselves are German.