That maximum cut limit on drums, really just to avoid the brake cylinders from going past their limit. Unless someone just runs those brakes to the end, rarely happens.
That's real possible, and easy to find out. Okay, OP, so your in Sweden. Cars in Sweden have brakes, too.
I'd suggest you pull BOTH rear brake cylinders, and take them apart. Simple things can make them not work, so they need to be looked at. Condition of the cylinder itself, maybe needs to be honed. The pistons clean, the rubber cups in good shape, and sealing good. Nothing special about them, besides size, so should be easy enough to find them, where your at. Make sure the bleeders are okay, and clear.
Guessing their gummed, or rusted up. As long as you get fluid to them, no reason those brakes shouldn't work.