So, the more I read about Cultivation, the less sense her actions and dialogue makes to me in regards to the Stormlight Archive story so far.
Up to the Interlude, she seems not interested in ending the conflict over Roshar. Just cultivating some people to take up the fight against Odium, or replacing Rayse. So, without Cultivation, or the Nightwatcher involvement, Rodium would have steamrolled Roshar, but at least the conflict would be over.
What of her endgame is not limited to the conflict with Odium but something else entirely? And as there are some hints regarding Adonalsium, what if her plan has to do with him?
There are some points which got me thinking:
She and Honor both settle on Roshar, against the agreement of the 16 not to get near to each other
Why did they both chose Roshar in the first place? A heavily invested place, with sprens running around, in a star system with other....interesting planets. A place assumingly engineered by Adonalasium for a specific purpose (no tectonial activities, no obliquity, continent shaped like a Julia Set....)
Per WoB, Odium needed permission from both Honor and Cultivation to also settle there. Why allow him in?
At least one Dawnshard is/was hidden on Roshar
The two voices whispering "Unite them" to Dalinar
So, what if she has the ultimate goal to reunite/reform Adonalasium? I mean obviously, 16 (now ~10) shards battling each other over the galaxy is not the best idea for anyone living there, be it Human, Singer, Dragon, Spren, Shards or whatever.
Either she realized this like the next day after the shattering or some time later, after Odium splintered the first shard. It may have to do with her being a dragon, but perhaps she is just the only sane one of the bunch (besides Hoid).
In this context, all her actions could be part of a master plan spanning the whole galaxy. E.g. perhaps she cultivated the heralds to cause the last desolation, as she needed the ~4500 year stagnation for the rest of the Shard-Planets to catch up to the Rosharan civilization. So I assume, her plan would be to cause a Shard-war across the galaxy and for this you would need opponents of mostly equal power.
Just so, that after all the other shards have battled each other to the ground, she (with the help of some "cultivated" individuals and perhaps the Dawnshards) unites the splitered pieces again. With herself as the vessel? Or maybe even someone else.