You could try acrylic, "Americana" brand from JoAnn's. It's inexpensive and, like other acrylics, it's meant to flex to some degree. It may show signs of cracking, but if you put it on thick at the ankle areas and plan for maintenance, then you'll probably be okay.
There's also craft paints, not just floral paints, that are acrylic or plastic flex-like when dry. If it can be applied to foam, then it should be safe for the pleather. You might want to look into a matte spray can of sealant which possibly may reduce the amount of scuffing and cracking that may happen. Any cracks that will appear are likely to appear where your toes flex the shoe and around the ankle.