peace Student,
I think you are mixing some issues. My understanding is as follows:
2:31 And He imparted unto Adam the names of all things; then He brought them within the ken of the angels and said: "Declare unto Me the names of these [things], if what you say is true. (i.e. if what you say is true about the successor/khalifatan)"
Bold refers back to:
2:30 Your Lord said to the controllers, "I am placing a successor on earth." They said, "Would You place in it he who would corrupt it, and shed blood, while we sing Your glory, and praise You?" He said, "I know what you do not know."
You will note what God says in blue. Thus the question asked by God to the angels/controllers in 2:31 was to demonstrate that God knows what they (the angels/controllers) do not know. This is confirmed by their response:
2:32 They said, "Glory be to You, we have no knowledge except what You have taught us, You are the Knowledgeable, the Wise."
Thus what they supposed/claimed about the successor in 2:30 may not be true. "Adam"/mankind has been given a special ability, and the story of "Adam"/mankind is about that, see my previous posts.
The point was in demonstrating God knows what they (angels/controllers) do not know, not whether they could remember names God taught them.
If God were to tell the angels/controllers the names AND Adam/mankind the names, then ask the angels/controllers the same question, what would you expect to happen? Would it demonstrate the point God knows what they do not know?