Thinking about the very specific 7:46 time and the fact that there seem to be illusions/lightweaving activity associated with Cusicesh, I wondered if there was any significance between the Knights Radiant, the nature of megaspren and that number.
The numbers 7, 4, 6 correspond to Battar/Elsecallers, Vedel/Edgedancers, and Shalash/Lightweavers. The illusions may suggest a connection to the Lightweavers, Cusicesh's ties to the cognitive realm a nod to the Elsecallers' proficiency there, and the faces to Edgedancers' oath to remember those who have been forgotten.
It is also possible that the Heralds and/or Knights Radiant might have a large spren, given that we know Stormfather is a spren manifestation of people's belief in Honor. Not sure how all this might fit together or exactly how Cusicesh came to be fixed in the bay, but there may be something there.