twilight, sunset
曛 centers on the dim, fading light of dusk: twilight and sunset, when the sun sinks and the sky darkens.
曛 combines 日 (sun) with 熏, which likely contributes the sound and the idea of smoke or dimness, together suggesting the hazy light of sunset.
The sun 日 is beside 熏, which looks like smoke rising from a fire. Picture the sun sinking into a smoky haze at twilight.
For クン, imagine a coon (raccoon) emerging at twilight: coon -> クン, and the raccoon appears as the sun sets.