The introduction of the Royal Restoration Spell on beta significantly restructured the way event buildings are stored in the game. This resulted in the city plans on Elven Architect to become "corrupted" and it would appear like these event buildings were missing.
It's been a "major headache" for the Inno developers to implement this spell, and has been the same for me to ensure city plans are preserved but I believe that they should all be working again. If you are still missing buildings, please let me know.
Thanks and happy new year!