I think this is an entirely acceptable feat to include. Sure, it bumps up the verse to an entirely higher tier than before, but from what i've read + played, nothing that's mentioned in this is anything that is particularly new or distinctive.
From what we have seen in Genshin's history, the idea of people creating pocket dimensions with their power alone is nothing new to the game itself. Domains have been part of the game since day 1, the Adeptus are capable of creating their own pocket dimensions (Including the Traveler's Teapot, which contains an entire day/night cycle complete with a Sun and Moon), and the Raiden Shogun's soul/Archon exists in the pocket dimension inside her
sword. This feat isn't any different from what I have mentioned before, so it would be a perfectly acceptable feat to include on the Genshin profile.
If you really wanted to be semantic about it, you could argue that the AP shown should be restricted only to the ability to manipulate Pocket Realities ( [X Tier]
4A with Pocket Reality Manipulation), but aside from the fact that I think it downplays the feat a bit too much, I would feel that having to create such a Pocket Reality should at least imply that said person should scale to at least a
portion of the Pocket Reality's AP (especially if consider the possibilty that it was created overtime). I mean, the
Imaginarum theater contains both stars and planets, so if anything that means that the Wizard should at least scale Star or Large Star Level or (if you REALLY want to nerf the feat) Planet/Large-Planet level since they would have to wield the power to create said stars/planets in the first place.