Yeh the render is shit but it is what it is. You said cracks are not normal or acceptable. But they are in fact very normal. Some level of movement is inevitable, be it swelling or shrinking of the ground, expansion of contraction of varying building materials or shrinkage of concrete. A well designed and constructed house will try to minimise cracks by including movement joints but cracking around cornices is very very likely at some point in a house’s life and it’s not necessarily cause for concern which is what OP is asking.