Not anything Belgian at all, for sure, in terms of production pieces. However, that definitely is Belgian Brushstroke pattern. There are a number of quite old, odd garments made out of non-standard cloth (i.e. official Belgian items did not use it) that have no absolute identification. They are cheaply made and come in a variety of different tailorings, though they seem to fit a common general pattern (epaulettes, 4 pockets with single button throughs, zipper front, attached hood, etc.). Buttons on them are similar to 1950s or early 1960s. Borsarello called it "Algerian", or some such thing, but there's no evidence offered. As we know, Borsarello's identifications should be taken with a fist full of salt.
My personal guess is they were cheap export items made in Belgium for African militias in the 1960s. This is consistent with the few facts we know about them, including the fact that they turn up in Europe every so often. I've got three and I know other collectors have examples as well.
Without feeling this item with my hands it's not possible to say exactly for sure, but I'd say the cloth appears to be the same as used for the mystery garments. It certainly is a common flight jacket design and Rhodie/SA guys had all kinds of stuff custom made for themselves. I'd start with that premise and see what the Rhodie/SA experts think of it.