I don't recall seeing anything definitive on ceruleum outside of it being an unstable, volatile, aetheric fuel source that goes into vapor form when in contact with the atmosphere. It does seem like an interesting coincidence that it's the same color as the aetheric sea and the mothercrystal, but it's really at the writers' discretion if they ever decide to draw a link between the two.

The impact of the Black Rose follows logically from Urianger's explanation in Shadowbringers, in that the 'Black Rose slayeth by halting the circulation of aether within living beings,' (Unto the Truth, Lv. 72). This is the natural consequence of a Calamity of Light derived from the flood of aspected light aether from the First, which brings about aetheric stasis. The description in Tales from the Shadows, A World Forsaken, fits with this as well: 'Due to the aftereffects of Black Rose, the ceruleum that once supported daily life in the Empire and powered its magitek armies failed to combust.' Again, a volatile aetheric compound is brought into stasis.

In contrast, you'd expect that a Darkness-aspected calamity might make ceruleum even more volatile, to the point of it being unusable as an aetheric energy source.