I've found that Trebuchet launcher doesn't have those graphic artifacts, caused by the placebocomposer. However, Nova Launcher has them and that makes me think you've found a way to fix the glitches in certain apps. If so, is it possible to implement these fixes to the daydream clock app? Also, I think that the analog daydream clock doesn't always glitch because it updates the screen every second, while the digital one does so every minute. Maybe if you make the digital clock update every second, the artifacts won't show?
Galaxy S4 · Exynos 5 Octa · Black Mist
Galaxy Note II · Titanium Gray