Word of God confirmation that the high priests actually did want Susebron and Siri to have a child very quickly, makes much of their behavior seem rather nonsensical. Particularly instructing Siri to quietly and passively wait for her husband, who has no idea how babies are made, to ravish her. And then not so subtly threatening her homeland with war when, predictably, no baby making occurred. This all makes much more sense when you eventually realize that the priests were relying on Bluefingers to handle all instructions related to coupling with Susebron. Whatever original instructions Siri was intended to receive to compensate for Susebron's ignorance of marital matters never reached her.
This also does a great deal to explain much of the priests Jerkass hostility towards Siri. While Siri laying in a nude Pose of Supplication before the God King for hours on end on her wedding night was terribly humiliating for her, to the priests it would have looked like deliberate act of defiance from the "fanatical" rebel Idris princess. Worse, seeing gentle Susebron being melodramatically kow-towed to look like he was some kind of brutal monster would have seemed a deliberate insult to the priests. Considering the Martyr Complex that Vivenna had towards being sent to wed the God King, it would have been easy to see Siri as a viper who needed to be forced into submission.
Lightsong's curious ability to juggle fruit and his inexplicable talent for Terachin might have a common root. Namely, he might have had a good throwing arm and excellent hand-eye coordination, beyond what was strictly necessary for his former life. Further evidence of this is the thing he set up to count the priests going in and coming out of the god's compounds - throwing pebbles, unerringly, from a reclined position, into one of several dishes.
Nightblood can't see and as such would depend on peoples surface thoughts to give it visual information. The majority of this information would come from Vasher. Now what does Nightblood thinks Vivenna looks like again?
Llarimar's seemingly bottomless ability to put up with Lightsong's antics makes a lot more sense when you find out that Lightsong was Llarimar's brother. Llarimar has had his entire life to get used to Lightsong acting out, and it therefore doesn't conflict with his devotion to Lightsong.
Lemex catches fever and dies just as Vivenna reaches him, resulting in the fortunate passing on of his Breath to her. The timing of the death is a large coincidence that slightly strains suspension of disbelief. However, the truth is that Denth is responsible for the death and the timing, revealed with his sudden betrayal.
It's mentioned that for more advanced Awakening, the exact wording of a Command can be very important (i.e. One of the contributing factors to the Manywar was the discovery of a Command that allowed for the creation of Lifeless with a single Breath, as opposed to the previous fifty). It's also mentioned that Commands only work if spoken in the Awakener's native tongue. Combined, these two factors explain why Awakening seems to be almost exclusively a Hallendren thing, even centuries after its discovery. Since Commands only work in the Awakener's native tongue, Commands discovered in Hallendren can't be used by non-native Hallendren speakers. And even if they translate the Commands, the exact wording, the subtleties that make such a difference, will be lost. Thus, each civilization on Nalthis must to a certain degree start from scratch in discovering Awakening. Even the command to transfer Breaths may take ages to discover in a new language, even if you know where to start from, and without that no real research is possible into other Commands.