If it satisfies anyone's curiosity (i.e. if anyone actually cares), I looked at the Ultimania credits pages to see exactly what is attributed to whom.
I decided the FFVII Ultimania Omega would be the most logical starting point. This is what it had to say:
出版・編集 (Publication and Editorial): Square Enix
企画・構成・執筆 (Planning, Constituion and Writing): Studio BentStuff
デザイン&DTP (Design and Desktop Publishing): Wan Inc.
カバーデザイン (Cover Design): Tadashi Shimada (Banana Studio)
インタビュー撮影 (Interview Photos): Handmade Co.
監修 (Editorial Supervision): Square Enix
Under each section are the names of the specific people involved and their respective contributions. Of most relevant note, under "Editorial Supervision," we find COMPILATION of FFVII 宣伝スタッフ (Compilation of FFVII Publicity Staff), 野村哲也 (Tetsuya Nomura) and 野島一成 (Kazushige Nojima).
From there, I checked the FFVII 10th Anniversary Ultimania. Under "Editorial Supervision" and "Collaboration" (協力
, we find Nojima and the Compilation publicity staff again. Nojima is again listed under "Collaboration" for the FF 20th Anniversary Ultimania File 2: Scenario guide, while Square Enix Publicity Department (宣伝部
is under both "Collaboration" and "Supervision" for this one. Finally, both the publicity department and the Respective Final Fantasy Series Development Teams (ファイナルファンタジーシリーズ各開発チーム
are listed under both "Collaboration" and "Editorial Supervision" for the FF 25th Memorial Ultimania Vol. 2.
As a reminder, Vol. 2 is the book that talks about VII, VIII and IX, two of which were games written by Nojima. For comparison's sake, the FFVIII Ultimania uses a similar blanket credit (ファイナルファンタジーVIII開発チーム/Final Fantasy VIII Development Team) for "Collaboration" and has a unique short story from Nojima.
I don't have the Crisis Core Ultimania to bother checking, but it stands to reason that similar names can be found there. It also stands to reason that Nojima has seen and approved of how the Ultimanias talk about Cloud and Tifa.
And, yes, I will agree (as I'm sure the point will be made) that this further legitimizes the canon status for Maiden Who Travels the Planet, despite later Ultimanias ignoring it. But, again, I still don't know why a Flowerfield Clerith would want that one to be canon anyway.
So, can we put this thing to bed now?