I understand your argument. But the decree itself described a change.
God spoke. He conversed. He listened. He received information. He introduced information. His anger was kindled, etc.
These are all changes, describing limited actions affordable within time's constraints.
How far up do you want to go?
G-d is Infinite and His flow of influence on the world is infinite, everything is there. There is no anger, there is no happiness, there is no anything, only unlimited flow of bounty that contains everything that could be, that causes everything. The constraining factor, is the vessel that receives it, the creation. According to the merit and ability of the creation to receive the bounty, that's what it receives, while the rest is halted at the degree above.
G-d's Anger, is describing that the recipient's merits and by extension its ability to receive the Divine Influence has decreased, resulting in a drop in quality of life. G-d's Happiness is describing the opposite. Even though the change is on the part of the recipient, we call it G-d's because we perceive it as a change in G-d's governance, not a change in ourselves. Ultimately though, this is working as G-d intends the system to work and it does so according to His Will.
The influence remains the same no matter the time or circumstances, what the change is the state of the recipient according to its merits and circumstances.