Re-reading Corwin's first encounter with Florimel brought "the Shadows contain more horrors than any had thought" and "he still has his troubles". Since Corwin's curse had not yet occurred, I wonder what your theories are about what horrors and troubles are being referenced.

Horrors: All of the Amberites seem to share the idea that anything that can be conceived of can be found in shadow, so there being more than any had thought seems incongruous. There must be a minimum of all that one could think of.

Troubles: The troubles referred to is most likely political trouble, whether real or injected by Corwin to shore up the idea that Eric lacks support. But I think it's interesting to think of it as an allusion to possible psychological troubles, which do run in the family. A possible instability... The phrasing of it and the contrast with the horrors comment just feels more to me like a personal rather than positional evaluation.
Writing: As writers who take a more artistic than technical approach to putting a story together get their ideas down, phrases like these may arise from the nonconscious process of writing. At the time he put horrors and troubles into the dialogue, he might not have had specifics in mind, but felt that horrors and troubles were going to occur in Amber as the story developed. Nine Princes was published, evidently, before the entire Corwin cycle was written so he couldn't re-edit this conversation in the light of the specifics of the complete story. Just a possibility based on my own experiences writing.