Well, it is true that main focus is around specific events for specific kingdoms, but it doesn't apply to Timfalme, where the story focuses exactly on investigating MC's condition, while Viridice-Lycalis war is just mentioned.
By the way, if it turns out that MC isn't a spy, then there will be no reason to keep him in the castle or even the kingdom. After all, it's a royal palace, not some random inn, and MC is not even a citizen of Timfalme, he got there simply because Sheina allowed it. He's still just a nobody from neutral territory with no job or place to stay.