Why is it you can evolve your Phoenix to level 9, then you get another pheonix and then can evolve the first one to level ten. That seems dumb. Why would I want another pheonix if I haven't evolved the first one to level ten? Someone needs to fix that. It's been like that for a bunch of events.
You're expected to also complete the questline, which grants two additional artifacts that will allow you to fully evolve the first phoenix before you receive the second one. This sort of breaks down if you spend diamonds to buy enough event tokens (Sky Essence, in this case) to reach the second phoenix before you can reach the second artifact in the questline, but you'll eventually be there in the end.
This pattern has held for just about every event with an evolving building that I've seen (since Sept. 2021), with evidence of it being that way for even longer.
The additional artifacts that you can get from a following Fellowship Adventures, otoh, hasn't been quite as reliable. Fairly reliable, but I've heard grumbling about missing artifacts here and there during my short-ish time here.
EDIT: The Magic Academy, during some of these events, temporarily gains recipes that allows you to exchange some of these current artifacts for one from an earlier event. If you (accidentally) craft some of these artifacts, then you might not be able to fully evolve the current event's evolving building. If that happened to you, and so long as you haven't actually spent the resulting artifact, try contacting support to get that reversed. idk if that'll work, but it seems like you can ask support for quite a number of things as compared to most other games.