Expanding on the scope of his impressive but constrained 2018 debut (the demonic-possession-meets-therapeutic-improv-exercise “Luz”) while retaining that film’s bird-flipping attitude toward unnecessary niceties like coherent plotting or narrative logic, German director Tilman Singer makes what ought to be his breakthrough with “Cuckoo” an energetically outlandish fusion of stylish atmospherics, old-school reproductive horror and pro-flickknife advertorial. […]