Good news! This issue has already been fed back to me via the Discord community. I have made changes to the turn order and it will be in this Friday's build.
As you say the AI adjusts their troops after the turn ends, this results in unfair engagements and bias against the player. In the new build the AI will deploy their troops at the start of the turn. This gives you more information about where the AI is strong, weak, etc.
The AI will adjust their troops too when you declare war, so no more land grabs at the start of a war. The Spring update this Friday has a ton of changes and it will add depth and more choices for how you manage your land forces and fight battles.
I have committed to supporting BfE for the whole of 2025. Economy and Navy will get overhauled in the Summer. Diplomacy in the Autumn. Tech and skill trees will be added in the Winter.