Goodbye 8th Year Event Goals Fix
A fix is now live. An additional goal, Earn 5 Stars, has been added. Completing this will grant the additional 500 RP to complete the reward track.
The ability to change nations (in addition to being able to delete a rebuild a different wonder) is something that has been requested many many times. I believe the developers are aware of this and will (hopefully) add this in soon.
Keep in mind there will probably be a small fee of crowns to change nation or delete wonder.